1 | /* $Id$ */ |
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2 | |
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3 | /* libi2c Implementation */ |
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4 | |
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5 | /* |
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6 | * Authorship |
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7 | * ---------- |
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8 | * This software was created by |
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9 | * Till Straumann <strauman@slac.stanford.edu>, 2005, |
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10 | * Stanford Linear Accelerator Center, Stanford University. |
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11 | * |
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12 | * Acknowledgement of sponsorship |
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13 | * ------------------------------ |
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14 | * This software was produced by |
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15 | * the Stanford Linear Accelerator Center, Stanford University, |
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16 | * under Contract DE-AC03-76SFO0515 with the Department of Energy. |
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17 | * |
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18 | * Government disclaimer of liability |
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19 | * ---------------------------------- |
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20 | * Neither the United States nor the United States Department of Energy, |
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21 | * nor any of their employees, makes any warranty, express or implied, or |
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22 | * assumes any legal liability or responsibility for the accuracy, |
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23 | * completeness, or usefulness of any data, apparatus, product, or process |
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24 | * disclosed, or represents that its use would not infringe privately owned |
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25 | * rights. |
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26 | * |
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27 | * Stanford disclaimer of liability |
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28 | * -------------------------------- |
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29 | * Stanford University makes no representations or warranties, express or |
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30 | * implied, nor assumes any liability for the use of this software. |
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31 | * |
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32 | * Stanford disclaimer of copyright |
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33 | * -------------------------------- |
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34 | * Stanford University, owner of the copyright, hereby disclaims its |
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35 | * copyright and all other rights in this software. Hence, anyone may |
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36 | * freely use it for any purpose without restriction. |
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37 | * |
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38 | * Maintenance of notices |
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39 | * ---------------------- |
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40 | * In the interest of clarity regarding the origin and status of this |
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41 | * SLAC software, this and all the preceding Stanford University notices |
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42 | * are to remain affixed to any copy or derivative of this software made |
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43 | * or distributed by the recipient and are to be affixed to any copy of |
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44 | * software made or distributed by the recipient that contains a copy or |
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45 | * derivative of this software. |
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46 | * |
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47 | * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03 |
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48 | */ |
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49 | #if HAVE_CONFIG_H |
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50 | #include "config.h" |
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51 | #endif |
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52 | |
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53 | #include <string.h> |
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54 | #include <stdio.h> |
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55 | #include <stdlib.h> |
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56 | #include <errno.h> |
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57 | #include <assert.h> |
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58 | |
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59 | #include <rtems.h> |
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60 | #include <rtems/error.h> |
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61 | #include <rtems/libio.h> |
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62 | |
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63 | #include <rtems/libi2c.h> |
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64 | |
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65 | #define DRVNM "libi2c:" |
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66 | |
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67 | #define MAX_NO_BUSSES 8 /* Also limited by the macro building minor numbers */ |
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68 | #define MAX_NO_DRIVERS 16 /* Number of high level drivers we support */ |
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69 | |
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70 | #define MINOR2ADDR(minor) ((minor)&((1<<10)-1)) |
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71 | #define MINOR2BUS(minor) (((minor)>>10)&7) |
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72 | #define MINOR2DRV(minor) ((minor)>>13) |
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73 | |
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74 | /* Check the 'minor' argument, i.e., verify that |
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75 | * we have a driver connected |
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76 | */ |
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77 | #define DECL_CHECKED_BH(b, bh, m, s)\ |
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78 | unsigned b = MINOR2BUS(m); \ |
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79 | rtems_libi2c_bus_t *bh; \ |
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80 | if ( b >= MAX_NO_BUSSES || 0 == (bh=busses[b].bush) ) { \ |
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81 | return s RTEMS_INVALID_NUMBER; \ |
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82 | } |
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83 | |
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84 | #define DECL_CHECKED_DRV(d, b, m) \ |
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85 | unsigned d = MINOR2DRV(m); \ |
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86 | unsigned b = MINOR2BUS(m); \ |
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87 | if ( b >= MAX_NO_BUSSES || 0 == busses[b].bush \ |
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88 | || d > MAX_NO_DRIVERS || (d && 0 == drvs[d-1].drv )) {\ |
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89 | return RTEMS_INVALID_NUMBER; \ |
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90 | } |
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91 | |
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92 | #define DISPATCH(rval, entry, dflt) \ |
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93 | do { \ |
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94 | rtems_driver_address_table *ops = drvs[--drv].drv->ops; \ |
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95 | rval = ops->entry ? ops->entry(major,minor,arg) : dflt; \ |
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96 | } while (0) |
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97 | |
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98 | |
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99 | rtems_device_major_number rtems_libi2c_major; |
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100 | |
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101 | static struct i2cbus |
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102 | { |
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103 | rtems_libi2c_bus_t *bush; |
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104 | volatile rtems_id mutex; /* lock this across start -> stop */ |
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105 | volatile short waiting; |
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106 | volatile char started; |
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107 | char *name; |
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108 | } busses[MAX_NO_BUSSES] = { { 0 } }; |
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109 | |
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110 | static struct |
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111 | { |
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112 | rtems_libi2c_drv_t *drv; |
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113 | } drvs[MAX_NO_DRIVERS] = { { 0} }; |
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114 | |
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115 | static rtems_id libmutex = 0; |
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116 | |
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117 | #define LOCK(m) assert(!rtems_semaphore_obtain((m), RTEMS_WAIT, RTEMS_NO_TIMEOUT)) |
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118 | #define UNLOCK(m) rtems_semaphore_release((m)) |
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119 | |
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120 | #define LIBLOCK() LOCK(libmutex) |
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121 | #define LIBUNLOCK() UNLOCK(libmutex) |
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122 | |
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123 | #define MUTEX_ATTS \ |
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124 | ( RTEMS_PRIORITY \ |
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125 | | RTEMS_BINARY_SEMAPHORE \ |
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126 | |RTEMS_INHERIT_PRIORITY \ |
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127 | |RTEMS_NO_PRIORITY_CEILING \ |
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128 | |RTEMS_LOCAL ) |
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129 | |
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130 | static rtems_id |
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131 | mutexCreate (rtems_name nm) |
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132 | { |
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133 | rtems_status_code sc; |
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134 | rtems_id rval; |
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135 | if (RTEMS_SUCCESSFUL != |
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136 | (sc = rtems_semaphore_create (nm, 1, MUTEX_ATTS, 0, &rval))) { |
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137 | rtems_error (sc, DRVNM " unable to create mutex\n"); |
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138 | return 0; |
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139 | } |
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140 | return rval; |
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141 | } |
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142 | |
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143 | /* Lock a bus avoiding to have a mutex, which is mostly |
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144 | * unused, hanging around all the time. We just create |
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145 | * and delete it on the fly... |
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146 | * |
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147 | * ASSUMES: argument checked by caller |
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148 | */ |
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149 | |
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150 | static void |
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151 | lock_bus (int busno) |
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152 | { |
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153 | struct i2cbus *bus = &busses[busno]; |
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154 | LIBLOCK (); |
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155 | if (!bus->waiting) { |
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156 | /* nobody is holding the bus mutex - it's not there. Create it on the fly */ |
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157 | if (! |
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158 | (bus->mutex = |
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159 | mutexCreate (rtems_build_name ('i', '2', 'c', '0' + busno)))) { |
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160 | LIBUNLOCK (); |
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161 | rtems_panic (DRVNM " unable to create bus lock"); |
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162 | } |
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163 | } |
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164 | /* count number of people waiting on this bus; only the last one deletes the mutex */ |
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165 | bus->waiting++; |
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166 | LIBUNLOCK (); |
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167 | /* Now lock this bus */ |
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168 | LOCK (bus->mutex); |
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169 | } |
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170 | |
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171 | static void |
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172 | unlock_bus (int busno) |
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173 | { |
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174 | struct i2cbus *bus = &busses[busno]; |
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175 | LIBLOCK (); |
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176 | UNLOCK (bus->mutex); |
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177 | if (!--bus->waiting) { |
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178 | rtems_semaphore_delete (bus->mutex); |
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179 | } |
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180 | LIBUNLOCK (); |
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181 | } |
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182 | |
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183 | /* Note that 'arg' is always passed in as NULL */ |
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184 | static rtems_status_code |
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185 | i2c_init (rtems_device_major_number major, rtems_device_minor_number minor, |
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186 | void *arg) |
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187 | { |
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188 | rtems_status_code rval; |
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189 | DECL_CHECKED_DRV (drv, busno, minor) |
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190 | |
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191 | if (0 == drv) { |
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192 | rval = 0; |
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193 | } else { |
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194 | /* this is probably never called */ |
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195 | DISPATCH (rval, initialization_entry, RTEMS_SUCCESSFUL); |
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196 | } |
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197 | return rval; |
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198 | } |
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199 | |
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200 | static rtems_status_code |
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201 | i2c_open (rtems_device_major_number major, rtems_device_minor_number minor, |
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202 | void *arg) |
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203 | { |
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204 | rtems_status_code rval; |
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205 | DECL_CHECKED_DRV (drv, busno, minor) |
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206 | |
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207 | if (0 == drv) { |
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208 | rval = RTEMS_SUCCESSFUL; |
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209 | } else { |
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210 | DISPATCH (rval, open_entry, RTEMS_SUCCESSFUL); |
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211 | } |
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212 | return rval; |
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213 | } |
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214 | |
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215 | static rtems_status_code |
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216 | i2c_close (rtems_device_major_number major, rtems_device_minor_number minor, |
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217 | void *arg) |
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218 | { |
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219 | rtems_status_code rval; |
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220 | DECL_CHECKED_DRV (drv, busno, minor) |
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221 | |
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222 | if (0 == drv) { |
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223 | rval = RTEMS_SUCCESSFUL; |
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224 | } else { |
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225 | DISPATCH (rval, close_entry, RTEMS_SUCCESSFUL); |
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226 | } |
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227 | return rval; |
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228 | } |
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229 | |
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230 | static rtems_status_code |
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231 | i2c_read (rtems_device_major_number major, rtems_device_minor_number minor, |
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232 | void *arg) |
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233 | { |
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234 | int rval; /* int so we can check for negative value */ |
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235 | rtems_libio_rw_args_t *rwargs = arg; |
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236 | DECL_CHECKED_DRV (drv, busno, minor) |
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237 | |
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238 | if (0 == rwargs->count) { |
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239 | rwargs->bytes_moved = 0; |
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240 | return RTEMS_SUCCESSFUL; |
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241 | } |
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242 | |
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243 | if (0 == drv) { |
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244 | rval = |
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245 | rtems_libi2c_start_read_bytes (minor, (unsigned char *) rwargs->buffer, |
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246 | rwargs->count); |
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247 | if (rval >= 0) { |
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248 | rwargs->bytes_moved = rval; |
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249 | rtems_libi2c_send_stop (minor); |
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250 | rval = RTEMS_SUCCESSFUL; |
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251 | } else { |
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252 | rval = -rval; |
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253 | } |
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254 | } else { |
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255 | DISPATCH (rval, read_entry, RTEMS_NOT_IMPLEMENTED); |
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256 | } |
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257 | return rval; |
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258 | } |
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259 | |
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260 | static rtems_status_code |
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261 | i2c_write (rtems_device_major_number major, rtems_device_minor_number minor, |
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262 | void *arg) |
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263 | { |
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264 | int rval; /* int so we can check for negative value */ |
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265 | rtems_libio_rw_args_t *rwargs = arg; |
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266 | DECL_CHECKED_DRV (drv, busno, minor) |
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267 | |
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268 | if (0 == rwargs->count) { |
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269 | rwargs->bytes_moved = 0; |
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270 | return RTEMS_SUCCESSFUL; |
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271 | } |
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272 | |
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273 | if (0 == drv) { |
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274 | rval = |
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275 | rtems_libi2c_start_write_bytes (minor, (unsigned char *) rwargs->buffer, |
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276 | rwargs->count); |
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277 | if (rval >= 0) { |
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278 | rwargs->bytes_moved = rval; |
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279 | rtems_libi2c_send_stop (minor); |
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280 | rval = RTEMS_SUCCESSFUL; |
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281 | } else { |
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282 | rval = -rval; |
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283 | } |
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284 | } else { |
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285 | DISPATCH (rval, write_entry, RTEMS_NOT_IMPLEMENTED); |
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286 | } |
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287 | return rval; |
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288 | } |
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289 | |
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290 | static rtems_status_code |
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291 | i2c_ioctl (rtems_device_major_number major, rtems_device_minor_number minor, |
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292 | void *arg) |
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293 | { |
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294 | rtems_status_code rval; |
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295 | DECL_CHECKED_DRV (drv, busno, minor) |
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296 | |
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297 | if (0 == drv) { |
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298 | rval = RTEMS_NOT_IMPLEMENTED; |
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299 | } else { |
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300 | DISPATCH (rval, control_entry, RTEMS_NOT_IMPLEMENTED); |
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301 | } |
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302 | return rval; |
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303 | } |
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304 | |
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305 | |
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306 | /* Our ops just dispatch to the registered drivers */ |
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307 | static rtems_driver_address_table libi2c_io_ops = { |
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308 | initialization_entry: i2c_init, |
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309 | open_entry: i2c_open, |
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310 | close_entry: i2c_close, |
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311 | read_entry: i2c_read, |
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312 | write_entry: i2c_write, |
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313 | control_entry: i2c_ioctl, |
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314 | }; |
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315 | |
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316 | |
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317 | int |
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318 | rtems_libi2c_initialize () |
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319 | { |
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320 | rtems_status_code sc; |
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321 | |
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322 | if (!(libmutex = mutexCreate (rtems_build_name ('l', 'I', '2', 'C')))) |
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323 | return -1; |
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324 | |
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325 | sc = rtems_io_register_driver (0, &libi2c_io_ops, &rtems_libi2c_major); |
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326 | if (RTEMS_SUCCESSFUL != sc) { |
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327 | fprintf (stderr, |
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328 | DRVNM " Claiming driver slot failed (rtems status code %i)\n", |
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329 | sc); |
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330 | rtems_semaphore_delete (libmutex); |
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331 | libmutex = 0; |
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332 | return -1; |
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333 | } |
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334 | |
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335 | return 0; |
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336 | } |
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337 | |
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338 | int |
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339 | rtems_libi2c_register_bus (char *name, rtems_libi2c_bus_t * bus) |
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340 | { |
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341 | int i; |
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342 | rtems_status_code err; |
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343 | char *nmcpy = malloc (name ? strlen (name) + 1 : 20); |
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344 | char tmp, *chpt; |
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345 | struct stat sbuf; |
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346 | |
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347 | strcpy (nmcpy, name ? name : "/dev/i2c"); |
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348 | |
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349 | |
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350 | /* check */ |
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351 | if ('/' != *nmcpy) { |
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352 | fprintf (stderr, |
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353 | "Bad name; must be an absolute path starting with '/'\n"); |
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354 | return -RTEMS_INVALID_NAME; |
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355 | } |
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356 | /* file must not exist */ |
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357 | if (!stat (nmcpy, &sbuf)) { |
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358 | fprintf (stderr, "Bad name; file exists already\n"); |
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359 | return -RTEMS_INVALID_NAME; |
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360 | } |
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361 | |
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362 | /* we already verified that there is at least one '/' */ |
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363 | chpt = strrchr (nmcpy, '/') + 1; |
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364 | tmp = *chpt; |
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365 | *chpt = 0; |
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366 | i = stat (nmcpy, &sbuf); |
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367 | *chpt = tmp; |
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368 | if (i) { |
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369 | fprintf (stderr, "Get %s status failed: %s\n", |
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370 | nmcpy,strerror(errno)); |
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371 | return -RTEMS_INVALID_NAME; |
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372 | } |
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373 | /* should be a directory since name terminates in '/' */ |
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374 | |
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375 | |
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376 | if (!libmutex) { |
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377 | fprintf (stderr, DRVNM " library not initialized\n"); |
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378 | return -RTEMS_NOT_DEFINED; |
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379 | } |
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380 | |
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381 | if (bus->size < sizeof (*bus)) { |
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382 | fprintf (stderr, DRVNM " bus-ops size too small -- misconfiguration?\n"); |
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383 | return -RTEMS_NOT_CONFIGURED; |
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384 | } |
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385 | |
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386 | LIBLOCK (); |
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387 | for (i = 0; i < MAX_NO_BUSSES; i++) { |
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388 | if (!busses[i].bush) { |
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389 | /* found a free slot */ |
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390 | busses[i].bush = bus; |
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391 | busses[i].mutex = 0; |
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392 | busses[i].waiting = 0; |
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393 | busses[i].started = 0; |
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394 | |
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395 | if (!name) |
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396 | sprintf (nmcpy + strlen (nmcpy), "%i", i); |
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397 | |
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398 | if ((err = busses[i].bush->ops->init (busses[i].bush))) { |
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399 | /* initialization failed */ |
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400 | i = -err; |
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401 | } else { |
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402 | busses[i].name = nmcpy;; |
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403 | nmcpy = 0; |
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404 | } |
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405 | |
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406 | break; |
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407 | } |
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408 | } |
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409 | LIBUNLOCK (); |
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410 | |
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411 | if (i >= MAX_NO_BUSSES) { |
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412 | i = -RTEMS_TOO_MANY; |
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413 | } |
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414 | |
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415 | free (nmcpy); |
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416 | |
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417 | return i; |
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418 | } |
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419 | |
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420 | static int |
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421 | not_started (int busno) |
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422 | { |
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423 | int rval; |
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424 | lock_bus (busno); |
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425 | rval = !busses[busno].started; |
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426 | unlock_bus (busno); |
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427 | return rval; |
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428 | } |
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429 | |
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430 | rtems_status_code |
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431 | rtems_libi2c_send_start (uint32_t minor) |
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432 | { |
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433 | int rval; |
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434 | DECL_CHECKED_BH (busno, bush, minor, +) |
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435 | |
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436 | lock_bus (busno); |
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437 | rval = bush->ops->send_start (bush); |
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438 | |
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439 | /* if this failed or is not the first start, unlock */ |
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440 | if (rval || busses[busno].started) { |
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441 | /* HMM - what to do if the 1st start failed ? |
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442 | * try to reset... |
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443 | */ |
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444 | if (!busses[busno].started) { |
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445 | /* just in case the bus driver fiddles with errno */ |
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446 | int errno_saved = errno; |
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447 | bush->ops->init (bush); |
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448 | errno = errno_saved; |
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449 | } else if (rval) { |
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450 | /* failed restart */ |
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451 | rtems_libi2c_send_stop (minor); |
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452 | } |
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453 | unlock_bus (busno); |
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454 | } else { |
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455 | /* successful 1st start; keep bus locked until stop is sent */ |
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456 | busses[busno].started = 1; |
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457 | } |
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458 | return rval; |
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459 | } |
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460 | |
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461 | rtems_status_code |
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462 | rtems_libi2c_send_stop (uint32_t minor) |
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463 | { |
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464 | rtems_status_code rval; |
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465 | DECL_CHECKED_BH (busno, bush, minor, +) |
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466 | |
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467 | if (not_started (busno)) |
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468 | return RTEMS_NOT_OWNER_OF_RESOURCE; |
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469 | |
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470 | rval = bush->ops->send_stop (bush); |
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471 | |
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472 | busses[busno].started = 0; |
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473 | |
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474 | unlock_bus (busno); |
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475 | return rval; |
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476 | } |
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477 | |
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478 | rtems_status_code |
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479 | rtems_libi2c_send_addr (uint32_t minor, int rw) |
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480 | { |
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481 | rtems_status_code sc; |
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482 | DECL_CHECKED_BH (busno, bush, minor, +) |
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483 | |
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484 | if (not_started (busno)) |
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485 | return RTEMS_NOT_OWNER_OF_RESOURCE; |
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486 | |
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487 | sc = bush->ops->send_addr (bush, MINOR2ADDR (minor), rw); |
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488 | if (RTEMS_SUCCESSFUL != sc) |
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489 | rtems_libi2c_send_stop (minor); |
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490 | return sc; |
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491 | } |
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492 | |
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493 | int |
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494 | rtems_libi2c_read_bytes (uint32_t minor, unsigned char *bytes, int nbytes) |
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495 | { |
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496 | int sc; |
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497 | DECL_CHECKED_BH (busno, bush, minor, -) |
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498 | |
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499 | if (not_started (busno)) |
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500 | return -RTEMS_NOT_OWNER_OF_RESOURCE; |
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501 | |
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502 | sc = bush->ops->read_bytes (bush, bytes, nbytes); |
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503 | if (sc < 0) |
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504 | rtems_libi2c_send_stop (minor); |
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505 | return sc; |
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506 | } |
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507 | |
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508 | int |
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509 | rtems_libi2c_write_bytes (uint32_t minor, unsigned char *bytes, int nbytes) |
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510 | { |
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511 | int sc; |
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512 | DECL_CHECKED_BH (busno, bush, minor, -) |
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513 | |
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514 | if (not_started (busno)) |
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515 | return -RTEMS_NOT_OWNER_OF_RESOURCE; |
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516 | |
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517 | sc = bush->ops->write_bytes (bush, bytes, nbytes); |
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518 | if (sc < 0) |
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519 | rtems_libi2c_send_stop (minor); |
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520 | return sc; |
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521 | } |
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522 | |
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523 | static int |
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524 | do_s_rw (uint32_t minor, unsigned char *bytes, int nbytes, int rw) |
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525 | { |
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526 | rtems_status_code sc; |
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527 | rtems_libi2c_bus_t *bush; |
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528 | |
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529 | if ((sc = rtems_libi2c_send_start (minor))) |
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530 | return -sc; |
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531 | |
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532 | /* at this point, we hold the bus and are sure the minor number is valid */ |
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533 | bush = busses[MINOR2BUS (minor)].bush; |
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534 | |
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535 | if ((sc = bush->ops->send_addr (bush, MINOR2ADDR (minor), rw))) { |
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536 | rtems_libi2c_send_stop (minor); |
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537 | return -sc; |
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538 | } |
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539 | |
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540 | if (rw) |
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541 | sc = bush->ops->read_bytes (bush, bytes, nbytes); |
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542 | else |
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543 | sc = bush->ops->write_bytes (bush, bytes, nbytes); |
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544 | |
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545 | if (sc < 0) { |
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546 | rtems_libi2c_send_stop (minor); |
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547 | } |
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548 | return sc; |
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549 | } |
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550 | |
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551 | int |
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552 | rtems_libi2c_start_read_bytes (uint32_t minor, unsigned char *bytes, |
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553 | int nbytes) |
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554 | { |
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555 | return do_s_rw (minor, bytes, nbytes, 1); |
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556 | } |
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557 | |
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558 | int |
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559 | rtems_libi2c_start_write_bytes (uint32_t minor, unsigned char *bytes, |
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560 | int nbytes) |
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561 | { |
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562 | return do_s_rw (minor, bytes, nbytes, 0); |
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563 | } |
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564 | |
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565 | int |
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566 | rtems_libi2c_register_drv (char *name, rtems_libi2c_drv_t * drvtbl, |
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567 | unsigned busno, unsigned i2caddr) |
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568 | { |
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569 | int i; |
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570 | rtems_status_code err; |
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571 | rtems_device_minor_number minor; |
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572 | |
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573 | if (!libmutex) { |
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574 | fprintf (stderr, DRVNM " library not initialized\n"); |
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575 | return -RTEMS_NOT_DEFINED; |
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576 | } |
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577 | |
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578 | if (name && strchr (name, '/')) { |
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579 | fprintf (stderr, "Invalid name: '%s' -- must not contain '/'\n", name); |
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580 | return -RTEMS_INVALID_NAME; |
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581 | } |
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582 | |
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583 | if (busno >= MAX_NO_BUSSES || !busses[busno].bush || i2caddr >= 1 << 10) { |
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584 | errno = EINVAL; |
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585 | return -RTEMS_INVALID_NUMBER; |
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586 | } |
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587 | |
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588 | if (drvtbl->size < sizeof (*drvtbl)) { |
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589 | fprintf (stderr, DRVNM " drv-ops size too small -- misconfiguration?\n"); |
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590 | return -RTEMS_NOT_CONFIGURED; |
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591 | } |
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592 | |
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593 | /* allocate slot */ |
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594 | LIBLOCK (); |
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595 | for (i = 0; i < MAX_NO_DRIVERS; i++) { |
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596 | /* driver # 0 is special, it is the built-in raw driver */ |
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597 | if (!drvs[i].drv) { |
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598 | char *str; |
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599 | dev_t dev; |
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600 | uint32_t mode; |
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601 | |
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602 | /* found a free slot; encode slot + 1 ! */ |
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603 | minor = ((i + 1) << 13) | RTEMS_LIBI2C_MAKE_MINOR (busno, i2caddr); |
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604 | |
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605 | if (name) { |
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606 | str = malloc (strlen (busses[busno].name) + strlen (name) + 2); |
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607 | sprintf (str, "%s.%s", busses[busno].name, name); |
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608 | |
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609 | dev = rtems_filesystem_make_dev_t (rtems_libi2c_major, minor); |
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610 | |
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611 | mode = 0111 | S_IFCHR; |
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612 | if (drvtbl->ops->read_entry) |
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613 | mode |= 0444; |
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614 | if (drvtbl->ops->write_entry) |
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615 | mode |= 0222; |
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616 | |
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617 | /* note that 'umask' is applied to 'mode' */ |
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618 | if (mknod (str, mode, dev)) { |
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619 | fprintf (stderr, |
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620 | "Creating device node failed: %s; you can try to do it manually...\n", |
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621 | strerror (errno)); |
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622 | } |
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623 | |
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624 | free (str); |
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625 | } |
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626 | |
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627 | drvs[i].drv = drvtbl; |
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628 | |
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629 | if (drvtbl->ops->initialization_entry) |
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630 | err = |
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631 | drvs[i].drv->ops->initialization_entry (rtems_libi2c_major, minor, |
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632 | 0); |
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633 | else |
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634 | err = RTEMS_SUCCESSFUL; |
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635 | |
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636 | LIBUNLOCK (); |
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637 | return err ? -err : minor; |
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638 | } |
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639 | } |
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640 | LIBUNLOCK (); |
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641 | return -RTEMS_TOO_MANY; |
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642 | } |
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