1 | /* |
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2 | * dpram.c |
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3 | * |
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4 | * MPC8xx dual-port RAM allocation routines |
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5 | * |
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6 | * Based on code (alloc860.c in eth_comm port) by |
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7 | * Jay Monkman (jmonkman@frasca.com), |
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8 | * which, in turn, is based on code by |
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9 | * W. Eric Norum (eric@skatter.usask.ca). |
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10 | * |
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11 | * |
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12 | * Modifications : |
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13 | * Copyright (c) 1999, National Research Council of Canada |
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14 | */ |
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15 | |
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16 | #include <bsp.h> |
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17 | #include <rtems/rtems/intr.h> |
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18 | #include <rtems/error.h> |
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19 | |
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20 | /* |
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21 | * Allocation order: |
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22 | * - Dual-Port RAM section 0 |
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23 | * - Dual-Port RAM section 1 |
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24 | * - Dual-Port RAM section 2 |
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25 | * - Dual-Port RAM section 3 |
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26 | * - Dual-Port RAM section 4 |
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27 | */ |
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28 | static struct { |
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29 | unsigned8 *base; |
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30 | unsigned int size; |
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31 | unsigned int used; |
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32 | } dpram_regions[] = { |
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33 | { (char *)&m8xx.dpram0[0], sizeof m8xx.dpram0, 0 }, |
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34 | { (char *)&m8xx.dpram1[0], sizeof m8xx.dpram1, 0 }, |
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35 | { (char *)&m8xx.dpram2[0], sizeof m8xx.dpram2, 0 }, |
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36 | { (char *)&m8xx.dpram3[0], sizeof m8xx.dpram3, 0 }, |
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37 | { (char *)&m8xx.dpram4[0], sizeof m8xx.dpram4, 0 }, |
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38 | }; |
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39 | |
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40 | #define NUM_DPRAM_REGIONS (sizeof(dpram_regions) / sizeof(dpram_regions[0])) |
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41 | |
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42 | void * |
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43 | m8xx_dpram_allocate( unsigned int byte_count ) |
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44 | { |
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45 | unsigned int i; |
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46 | ISR_Level level; |
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47 | void *blockp = NULL; |
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48 | |
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49 | byte_count = (byte_count + 3) & ~0x3; |
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50 | |
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51 | /* |
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52 | * Running with interrupts disabled is usually considered bad |
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53 | * form, but this routine is probably being run as part of an |
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54 | * initialization sequence so the effect shouldn't be too severe. |
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55 | */ |
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56 | _ISR_Disable (level); |
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57 | |
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58 | for ( i = 0; i < NUM_DPRAM_REGIONS; i++ ) { |
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59 | /* |
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60 | * Verify that the region is available for use. |
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61 | * This test is necessary because if extra microcode modules |
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62 | * are installed, some regions are locked and unavailable. |
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63 | * See MPC860 User's Manual Pages 19-9 to 19-11. |
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64 | */ |
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65 | if (dpram_regions[i].used == 0) { |
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66 | volatile unsigned char *cp = dpram_regions[i].base; |
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67 | *cp = 0xAA; |
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68 | if (*cp != 0xAA) |
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69 | dpram_regions[i].used = dpram_regions[i].size; |
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70 | else { |
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71 | *cp = 0x55; |
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72 | if (*cp != 0x55) |
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73 | dpram_regions[i].used = dpram_regions[i].size; |
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74 | } |
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75 | *cp = 0x0; |
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76 | } |
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77 | if (dpram_regions[i].size - dpram_regions[i].used >= byte_count) { |
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78 | blockp = dpram_regions[i].base + dpram_regions[i].used; |
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79 | dpram_regions[i].used += byte_count; |
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80 | break; |
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81 | } |
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82 | } |
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83 | |
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84 | _ISR_Enable(level); |
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85 | |
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86 | if (blockp == NULL) |
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87 | rtems_panic("Can't allocate %d bytes of dual-port RAM.\n", byte_count); |
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88 | return blockp; |
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89 | } |
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