drivers/power/reset/at91-reset.c

   1 /*
   2  * Atmel AT91 SAM9 & SAMA5 SoCs reset code
   3  *
   4  * Copyright (C) 2007 Atmel Corporation.
   5  * Copyright (C) BitBox Ltd 2010
   6  * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcosoft.com>
   7  * Copyright (C) 2014 Free Electrons
   8  *
   9  * This file is licensed under the terms of the GNU General Public
  10  * License version 2.  This program is licensed "as is" without any
  11  * warranty of any kind, whether express or implied.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17 #include <linux/of_address.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/reboot.h>
  20
  21 #include <soc/at91/at91sam9_ddrsdr.h>
  22 #include <soc/at91/at91sam9_sdramc.h>
  23
  24 #define AT91_RSTC_CR    0x00            /* Reset Controller Control Register */
  25 #define AT91_RSTC_PROCRST       BIT(0)          /* Processor Reset */
  26 #define AT91_RSTC_PERRST        BIT(2)          /* Peripheral Reset */
  27 #define AT91_RSTC_EXTRST        BIT(3)          /* External Reset */
  28 #define AT91_RSTC_KEY           (0xa5 << 24)    /* KEY Password */
  29
  30 #define AT91_RSTC_SR    0x04            /* Reset Controller Status Register */
  31 #define AT91_RSTC_URSTS         BIT(0)          /* User Reset Status */
  32 #define AT91_RSTC_RSTTYP        GENMASK(10, 8)  /* Reset Type */
  33 #define AT91_RSTC_NRSTL         BIT(16)         /* NRST Pin Level */
  34 #define AT91_RSTC_SRCMP         BIT(17)         /* Software Reset Command in Progress */
  35
  36 #define AT91_RSTC_MR    0x08            /* Reset Controller Mode Register */
  37 #define AT91_RSTC_URSTEN        BIT(0)          /* User Reset Enable */
  38 #define AT91_RSTC_URSTIEN       BIT(4)          /* User Reset Interrupt Enable */
  39 #define AT91_RSTC_ERSTL         GENMASK(11, 8)  /* External Reset Length */
  40
  41 enum reset_type {
  42         RESET_TYPE_GENERAL      = 0,
  43         RESET_TYPE_WAKEUP       = 1,
  44         RESET_TYPE_WATCHDOG     = 2,
  45         RESET_TYPE_SOFTWARE     = 3,
  46         RESET_TYPE_USER         = 4,
  47 };
  48
  49 static void __iomem *at91_ramc_base[2], *at91_rstc_base;
  50 static struct clk *sclk;
  51
  52 /*
  53 * unless the SDRAM is cleanly shutdown before we hit the
  54 * reset register it can be left driving the data bus and
  55 * killing the chance of a subsequent boot from NAND
  56 */
  57 static int at91sam9260_restart(struct notifier_block *this, unsigned long mode,
  58                                void *cmd)
  59 {
  60         asm volatile(
  61                 /* Align to cache lines */
  62                 ".balign 32\n\t"
  63
  64                 /* Disable SDRAM accesses */
  65                 "str    %2, [%0, #" __stringify(AT91_SDRAMC_TR) "]\n\t"
  66
  67                 /* Power down SDRAM */
  68                 "str    %3, [%0, #" __stringify(AT91_SDRAMC_LPR) "]\n\t"
  69
  70                 /* Reset CPU */
  71                 "str    %4, [%1, #" __stringify(AT91_RSTC_CR) "]\n\t"
  72
  73                 "b      .\n\t"
  74                 :
  75                 : "r" (at91_ramc_base[0]),
  76                   "r" (at91_rstc_base),
  77                   "r" (1),
  78                   "r" cpu_to_le32(AT91_SDRAMC_LPCB_POWER_DOWN),
  79                   "r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST));
  80
  81         return NOTIFY_DONE;
  82 }
  83
  84 static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
  85                                void *cmd)
  86 {
  87         asm volatile(
  88                 /*
  89                  * Test wether we have a second RAM controller to care
  90                  * about.
  91                  *
  92                  * First, test that we can dereference the virtual address.
  93                  */
  94                 "cmp    %1, #0\n\t"
  95                 "beq    1f\n\t"
  96
  97                 /* Then, test that the RAM controller is enabled */
  98                 "ldr    r0, [%1]\n\t"
  99                 "cmp    r0, #0\n\t"
 100
 101                 /* Align to cache lines */
 102                 ".balign 32\n\t"
 103
 104                 /* Disable SDRAM0 accesses */
 105                 "1:     str     %3, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
 106                 /* Power down SDRAM0 */
 107                 "       str     %4, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
 108                 /* Disable SDRAM1 accesses */
 109                 "       strne   %3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
 110                 /* Power down SDRAM1 */
 111                 "       strne   %4, [%1, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
 112                 /* Reset CPU */
 113                 "       str     %5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
 114
 115                 "       b       .\n\t"
 116                 :
 117                 : "r" (at91_ramc_base[0]),
 118                   "r" (at91_ramc_base[1]),
 119                   "r" (at91_rstc_base),
 120                   "r" (1),
 121                   "r" cpu_to_le32(AT91_DDRSDRC_LPCB_POWER_DOWN),
 122                   "r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST)
 123                 : "r0");
 124
 125         return NOTIFY_DONE;
 126 }
 127
 128 static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
 129                            void *cmd)
 130 {
 131         writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
 132                at91_rstc_base);
 133
 134         return NOTIFY_DONE;
 135 }
 136
 137 static int samx7_restart(struct notifier_block *this, unsigned long mode,
 138                          void *cmd)
 139 {
 140         writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PROCRST),
 141                at91_rstc_base);
 142
 143         return NOTIFY_DONE;
 144 }
 145
 146 static void __init at91_reset_status(struct platform_device *pdev)
 147 {
 148         const char *reason;
 149         u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
 150
 151         switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
 152         case RESET_TYPE_GENERAL:
 153                 reason = "general reset";
 154                 break;
 155         case RESET_TYPE_WAKEUP:
 156                 reason = "wakeup";
 157                 break;
 158         case RESET_TYPE_WATCHDOG:
 159                 reason = "watchdog reset";
 160                 break;
 161         case RESET_TYPE_SOFTWARE:
 162                 reason = "software reset";
 163                 break;
 164         case RESET_TYPE_USER:
 165                 reason = "user reset";
 166                 break;
 167         default:
 168                 reason = "unknown reset";
 169                 break;
 170         }
 171
 172         dev_info(&pdev->dev, "Starting after %s\n", reason);
 173 }
 174
 175 static const struct of_device_id at91_ramc_of_match[] = {
 176         { .compatible = "atmel,at91sam9260-sdramc", },
 177         { .compatible = "atmel,at91sam9g45-ddramc", },
 178         { /* sentinel */ }
 179 };
 180
 181 static const struct of_device_id at91_reset_of_match[] = {
 182         { .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
 183         { .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
 184         { .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
 185         { .compatible = "atmel,samx7-rstc", .data = samx7_restart },
 186         { /* sentinel */ }
 187 };
 188 MODULE_DEVICE_TABLE(of, at91_reset_of_match);
 189
 190 static struct notifier_block at91_restart_nb = {
 191         .priority = 192,
 192 };
 193
 194 static int __init at91_reset_probe(struct platform_device *pdev)
 195 {
 196         const struct of_device_id *match;
 197         struct device_node *np;
 198         int ret, idx = 0;
 199
 200         at91_rstc_base = of_iomap(pdev->dev.of_node, 0);
 201         if (!at91_rstc_base) {
 202                 dev_err(&pdev->dev, "Could not map reset controller address\n");
 203                 return -ENODEV;
 204         }
 205
 206         if (!of_device_is_compatible(pdev->dev.of_node, "atmel,sama5d3-rstc")) {
 207                 /* we need to shutdown the ddr controller, so get ramc base */
 208                 for_each_matching_node(np, at91_ramc_of_match) {
 209                         at91_ramc_base[idx] = of_iomap(np, 0);
 210                         if (!at91_ramc_base[idx]) {
 211                                 dev_err(&pdev->dev, "Could not map ram controller address\n");
 212                                 of_node_put(np);
 213                                 return -ENODEV;
 214                         }
 215                         idx++;
 216                 }
 217         }
 218
 219         match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
 220         at91_restart_nb.notifier_call = match->data;
 221
 222         sclk = devm_clk_get(&pdev->dev, NULL);
 223         if (IS_ERR(sclk))
 224                 return PTR_ERR(sclk);
 225
 226         ret = clk_prepare_enable(sclk);
 227         if (ret) {
 228                 dev_err(&pdev->dev, "Could not enable slow clock\n");
 229                 return ret;
 230         }
 231
 232         ret = register_restart_handler(&at91_restart_nb);
 233         if (ret) {
 234                 clk_disable_unprepare(sclk);
 235                 return ret;
 236         }
 237
 238         at91_reset_status(pdev);
 239
 240         return 0;
 241 }
 242
 243 static int __exit at91_reset_remove(struct platform_device *pdev)
 244 {
 245         unregister_restart_handler(&at91_restart_nb);
 246         clk_disable_unprepare(sclk);
 247
 248         return 0;
 249 }
 250
 251 static struct platform_driver at91_reset_driver = {
 252         .remove = __exit_p(at91_reset_remove),
 253         .driver = {
 254                 .name = "at91-reset",
 255                 .of_match_table = at91_reset_of_match,
 256         },
 257 };
 258 module_platform_driver_probe(at91_reset_driver, at91_reset_probe);
 259
 260 MODULE_AUTHOR("Atmel Corporation");
 261 MODULE_DESCRIPTION("Reset driver for Atmel SoCs");
 262 MODULE_LICENSE("GPL v2");