[78111c3] | 1 | /* $Id$ */ |
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| 2 | |
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| 3 | /* Trivial i2c driver for the maxim DS1621 temperature sensor; |
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| 4 | * just implements reading constant conversions with 8-bit |
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| 5 | * resolution. |
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| 6 | * Demonstrates the implementation of a i2c high-level driver. |
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| 7 | */ |
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| 8 | |
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[3495c57] | 9 | /* |
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[6b184e0] | 10 | * Authorship |
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| 11 | * ---------- |
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| 12 | * This software was created by |
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| 13 | * Till Straumann <strauman@slac.stanford.edu>, 2005, |
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| 14 | * Stanford Linear Accelerator Center, Stanford University. |
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[3495c57] | 15 | * |
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[6b184e0] | 16 | * Acknowledgement of sponsorship |
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| 17 | * ------------------------------ |
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| 18 | * This software was produced by |
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| 19 | * the Stanford Linear Accelerator Center, Stanford University, |
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| 20 | * under Contract DE-AC03-76SFO0515 with the Department of Energy. |
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[3495c57] | 21 | * |
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[6b184e0] | 22 | * Government disclaimer of liability |
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| 23 | * ---------------------------------- |
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| 24 | * Neither the United States nor the United States Department of Energy, |
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| 25 | * nor any of their employees, makes any warranty, express or implied, or |
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| 26 | * assumes any legal liability or responsibility for the accuracy, |
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| 27 | * completeness, or usefulness of any data, apparatus, product, or process |
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| 28 | * disclosed, or represents that its use would not infringe privately owned |
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| 29 | * rights. |
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[3495c57] | 30 | * |
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[6b184e0] | 31 | * Stanford disclaimer of liability |
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| 32 | * -------------------------------- |
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| 33 | * Stanford University makes no representations or warranties, express or |
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| 34 | * implied, nor assumes any liability for the use of this software. |
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[3495c57] | 35 | * |
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[6b184e0] | 36 | * Stanford disclaimer of copyright |
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| 37 | * -------------------------------- |
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| 38 | * Stanford University, owner of the copyright, hereby disclaims its |
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| 39 | * copyright and all other rights in this software. Hence, anyone may |
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[3495c57] | 40 | * freely use it for any purpose without restriction. |
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| 41 | * |
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[6b184e0] | 42 | * Maintenance of notices |
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| 43 | * ---------------------- |
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| 44 | * In the interest of clarity regarding the origin and status of this |
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| 45 | * SLAC software, this and all the preceding Stanford University notices |
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| 46 | * are to remain affixed to any copy or derivative of this software made |
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| 47 | * or distributed by the recipient and are to be affixed to any copy of |
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| 48 | * software made or distributed by the recipient that contains a copy or |
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| 49 | * derivative of this software. |
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[3495c57] | 50 | * |
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[6b184e0] | 51 | * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03 |
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[3495c57] | 52 | */ |
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[78111c3] | 53 | #include <rtems.h> |
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| 54 | #include <rtems/libi2c.h> |
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| 55 | |
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| 56 | #include <libchip/i2c-ds1621.h> |
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| 57 | |
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| 58 | #include <rtems/libio.h> |
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| 59 | |
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| 60 | |
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| 61 | static rtems_status_code |
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| 62 | ds1621_init (rtems_device_major_number major, rtems_device_minor_number minor, |
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| 63 | void *arg) |
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| 64 | { |
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| 65 | int sc; |
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[34fe0e0] | 66 | unsigned char csr[2] = { DS1621_CMD_CSR_ACCESS, 0 }, cmd; |
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[78111c3] | 67 | |
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| 68 | /* First start command acquires a lock for the bus */ |
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| 69 | |
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| 70 | /* Initialize; switch continuous conversion on */ |
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| 71 | sc = rtems_libi2c_start_write_bytes (minor, csr, 1); |
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| 72 | if (sc < 0) |
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| 73 | return -sc; |
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| 74 | |
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| 75 | sc = rtems_libi2c_start_read_bytes (minor, csr + 1, 1); |
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| 76 | if (sc < 0) |
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| 77 | return -sc; |
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| 78 | |
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| 79 | csr[1] &= ~DS1621_CSR_1SHOT; |
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| 80 | |
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| 81 | sc = rtems_libi2c_start_write_bytes (minor, csr, 2); |
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| 82 | if (sc < 0) |
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| 83 | return -sc; |
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| 84 | |
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| 85 | /* Start conversion */ |
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| 86 | cmd = DS1621_CMD_START_CONV; |
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| 87 | |
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| 88 | sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1); |
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| 89 | if (sc < 0) |
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| 90 | return -sc; |
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| 91 | |
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| 92 | /* sending 'stop' relinquishes the bus mutex -- don't hold it |
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| 93 | * across system calls! |
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| 94 | */ |
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| 95 | return rtems_libi2c_send_stop (minor); |
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| 96 | } |
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| 97 | |
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| 98 | static rtems_status_code |
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| 99 | ds1621_read (rtems_device_major_number major, rtems_device_minor_number minor, |
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| 100 | void *arg) |
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| 101 | { |
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| 102 | int sc; |
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| 103 | rtems_libio_rw_args_t *rwargs = arg; |
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[34fe0e0] | 104 | unsigned char cmd = DS1621_CMD_READ_TEMP; |
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[78111c3] | 105 | |
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| 106 | sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1); |
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| 107 | if (sc < 0) |
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| 108 | return -sc; |
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| 109 | if (sc < 1) |
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| 110 | return RTEMS_IO_ERROR; |
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[34fe0e0] | 111 | sc = rtems_libi2c_start_read_bytes(minor, (unsigned char *)rwargs->buffer, 1); |
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[78111c3] | 112 | if (sc < 0) { |
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| 113 | rwargs->bytes_moved = 0; |
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| 114 | return -sc; |
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| 115 | } |
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| 116 | rwargs->bytes_moved = 1; |
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| 117 | return rtems_libi2c_send_stop (minor); |
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| 118 | } |
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| 119 | |
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| 120 | static rtems_driver_address_table myops = { |
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[06a36cd1] | 121 | .initialization_entry = ds1621_init, |
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| 122 | .read_entry = ds1621_read, |
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[78111c3] | 123 | }; |
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| 124 | |
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| 125 | static rtems_libi2c_drv_t my_drv_tbl = { |
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[06a36cd1] | 126 | .ops = &myops, |
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| 127 | .size = sizeof (my_drv_tbl), |
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[78111c3] | 128 | }; |
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| 129 | |
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| 130 | rtems_libi2c_drv_t *i2c_ds1621_driver_descriptor = &my_drv_tbl; |
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