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   1 /*
   2  * Copyright © 2019 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <ao.h>
  20 #include <ao_flash.h>
  21 #include <stdio.h>
  22
  23 /* Erase rows are four pages */
  24 static uint32_t
  25 samd21_nvmctrl_row_size(void)
  26 {
  27         return samd21_nvmctrl_page_size() * 4;
  28 }
  29
  30 /* size of a lock region. That's just total flash size / 16 */
  31 static uint32_t
  32 samd21_nvmctrl_lock_region(void)
  33 {
  34         return samd21_flash_size() >> 4;
  35 }
  36
  37 /* Find the bit index of an address within the lock word */
  38 static uint8_t
  39 ao_flash_lock_region_bit(void *addr)
  40 {
  41         return (uint8_t) (((uintptr_t) addr) / samd21_nvmctrl_lock_region());
  42 }
  43
  44 static uint8_t
  45 ao_flash_is_locked(void *addr)
  46 {
  47         return (samd21_nvmctrl.lock >> ao_flash_lock_region_bit(addr)) & 1;
  48 }
  49
  50 /* Execute a single flash operation, waiting for it to complete. This
  51  * bit of code must be in ram
  52  */
  53 static void __attribute__ ((section(".sdata2.flash"), noinline))
  54 _ao_flash_execute(uint16_t cmd)
  55 {
  56         while ((samd21_nvmctrl.intflag & (1 << SAMD21_NVMCTRL_INTFLAG_READY)) == 0)
  57                 ;
  58         samd21_nvmctrl.ctrla = ((cmd << SAMD21_NVMCTRL_CTRLA_CMD) |
  59                                 (SAMD21_NVMCTRL_CTRLA_CMDEX_KEY << SAMD21_NVMCTRL_CTRLA_CMDEX));
  60         while ((samd21_nvmctrl.intflag & (1 << SAMD21_NVMCTRL_INTFLAG_READY)) == 0)
  61                 ;
  62         samd21_nvmctrl.intflag = ((1 << SAMD21_NVMCTRL_INTFLAG_READY) |
  63                                   (1 << SAMD21_NVMCTRL_INTFLAG_ERROR));
  64 }
  65
  66 /* Set the address of the next flash operation */
  67 static void
  68 _ao_flash_set_addr(void *addr)
  69 {
  70         while ((samd21_nvmctrl.intflag & (1 << SAMD21_NVMCTRL_INTFLAG_READY)) == 0)
  71                 ;
  72         samd21_nvmctrl.addr = ((uint32_t) addr) >> 1;
  73         while ((samd21_nvmctrl.intflag & (1 << SAMD21_NVMCTRL_INTFLAG_READY)) == 0)
  74                 ;
  75 }
  76
  77 /* Unlock a region of flash */
  78 static void
  79 _ao_flash_unlock(void *addr)
  80 {
  81         if (!ao_flash_is_locked(addr))
  82                 return;
  83
  84         _ao_flash_set_addr(addr);
  85         _ao_flash_execute(SAMD21_NVMCTRL_CTRLA_CMD_UR);
  86 }
  87
  88 /* Erase a row of flash */
  89 static void
  90 _ao_flash_erase_row(void *row)
  91 {
  92         _ao_flash_unlock(row);
  93         _ao_flash_set_addr(row);
  94         _ao_flash_execute(SAMD21_NVMCTRL_CTRLA_CMD_ER);
  95 }
  96
  97 void
  98 ao_flash_erase_page(uint32_t *page)
  99 {
 100         uint8_t *row = (uint8_t *) page;
 101         uint32_t row_size = samd21_nvmctrl_row_size();
 102         uint32_t rows = (row_size + 255) / 256;
 103
 104         ao_arch_block_interrupts();
 105
 106         if (((uintptr_t) row & (row_size - 1)) == 0) {
 107                 while (rows--) {
 108                         _ao_flash_erase_row(row);
 109                         row += row_size;
 110                 }
 111         }
 112
 113         ao_arch_release_interrupts();
 114 }
 115
 116 void
 117 ao_flash_page(uint32_t *page, uint32_t *src)
 118 {
 119         uint32_t        page_size = samd21_nvmctrl_page_size();
 120         uint32_t        pages = 256 / page_size;
 121         uint32_t        i;
 122         uint32_t        per_page = page_size / sizeof(uint32_t);
 123
 124         ao_arch_block_interrupts();
 125
 126         while(pages--) {
 127                 /* Clear write buffer */
 128                 _ao_flash_execute(SAMD21_NVMCTRL_CTRLA_CMD_PBC);
 129                 _ao_flash_set_addr(page);
 130                 for (i = 0; i < per_page; i++)
 131                         *page++ = *src++;
 132                 _ao_flash_execute(SAMD21_NVMCTRL_CTRLA_CMD_WP);
 133         }
 134
 135         ao_arch_release_interrupts();
 136 }
 137