kernel/drivers/power/reset/at91-poweroff.c

   1 /*
   2  * Atmel AT91 SAM9 SoCs reset code
   3  *
   4  * Copyright (C) 2007 Atmel Corporation.
   5  * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
   6  * Copyright (C) 2014 Free Electrons
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/printk.h>
  19
  20 #define AT91_SHDW_CR    0x00            /* Shut Down Control Register */
  21 #define AT91_SHDW_SHDW          BIT(0)                  /* Shut Down command */
  22 #define AT91_SHDW_KEY           (0xa5 << 24)            /* KEY Password */
  23
  24 #define AT91_SHDW_MR    0x04            /* Shut Down Mode Register */
  25 #define AT91_SHDW_WKMODE0       GENMASK(2, 0)           /* Wake-up 0 Mode Selection */
  26 #define AT91_SHDW_CPTWK0_MAX    0xf                     /* Maximum Counter On Wake Up 0 */
  27 #define AT91_SHDW_CPTWK0        (AT91_SHDW_CPTWK0_MAX << 4) /* Counter On Wake Up 0 */
  28 #define AT91_SHDW_CPTWK0_(x)    ((x) << 4)
  29 #define AT91_SHDW_RTTWKEN       BIT(16)                 /* Real Time Timer Wake-up Enable */
  30 #define AT91_SHDW_RTCWKEN       BIT(17)                 /* Real Time Clock Wake-up Enable */
  31
  32 #define AT91_SHDW_SR    0x08            /* Shut Down Status Register */
  33 #define AT91_SHDW_WAKEUP0       BIT(0)                  /* Wake-up 0 Status */
  34 #define AT91_SHDW_RTTWK         BIT(16)                 /* Real-time Timer Wake-up */
  35 #define AT91_SHDW_RTCWK         BIT(17)                 /* Real-time Clock Wake-up [SAM9RL] */
  36
  37 enum wakeup_type {
  38         AT91_SHDW_WKMODE0_NONE          = 0,
  39         AT91_SHDW_WKMODE0_HIGH          = 1,
  40         AT91_SHDW_WKMODE0_LOW           = 2,
  41         AT91_SHDW_WKMODE0_ANYLEVEL      = 3,
  42 };
  43
  44 static const char *shdwc_wakeup_modes[] = {
  45         [AT91_SHDW_WKMODE0_NONE]        = "none",
  46         [AT91_SHDW_WKMODE0_HIGH]        = "high",
  47         [AT91_SHDW_WKMODE0_LOW]         = "low",
  48         [AT91_SHDW_WKMODE0_ANYLEVEL]    = "any",
  49 };
  50
  51 static void __iomem *at91_shdwc_base;
  52 static struct clk *sclk;
  53
  54 static void __init at91_wakeup_status(void)
  55 {
  56         u32 reg = readl(at91_shdwc_base + AT91_SHDW_SR);
  57         char *reason = "unknown";
  58
  59         /* Simple power-on, just bail out */
  60         if (!reg)
  61                 return;
  62
  63         if (reg & AT91_SHDW_RTTWK)
  64                 reason = "RTT";
  65         else if (reg & AT91_SHDW_RTCWK)
  66                 reason = "RTC";
  67
  68         pr_info("AT91: Wake-Up source: %s\n", reason);
  69 }
  70
  71 static void at91_poweroff(void)
  72 {
  73         writel(AT91_SHDW_KEY | AT91_SHDW_SHDW, at91_shdwc_base + AT91_SHDW_CR);
  74 }
  75
  76 static int at91_poweroff_get_wakeup_mode(struct device_node *np)
  77 {
  78         const char *pm;
  79         unsigned int i;
  80         int err;
  81
  82         err = of_property_read_string(np, "atmel,wakeup-mode", &pm);
  83         if (err < 0)
  84                 return AT91_SHDW_WKMODE0_ANYLEVEL;
  85
  86         for (i = 0; i < ARRAY_SIZE(shdwc_wakeup_modes); i++)
  87                 if (!strcasecmp(pm, shdwc_wakeup_modes[i]))
  88                         return i;
  89
  90         return -ENODEV;
  91 }
  92
  93 static void at91_poweroff_dt_set_wakeup_mode(struct platform_device *pdev)
  94 {
  95         struct device_node *np = pdev->dev.of_node;
  96         int wakeup_mode;
  97         u32 mode = 0, tmp;
  98
  99         wakeup_mode = at91_poweroff_get_wakeup_mode(np);
 100         if (wakeup_mode < 0) {
 101                 dev_warn(&pdev->dev, "shdwc unknown wakeup mode\n");
 102                 return;
 103         }
 104
 105         if (!of_property_read_u32(np, "atmel,wakeup-counter", &tmp)) {
 106                 if (tmp > AT91_SHDW_CPTWK0_MAX) {
 107                         dev_warn(&pdev->dev,
 108                                  "shdwc wakeup counter 0x%x > 0x%x reduce it to 0x%x\n",
 109                                  tmp, AT91_SHDW_CPTWK0_MAX, AT91_SHDW_CPTWK0_MAX);
 110                         tmp = AT91_SHDW_CPTWK0_MAX;
 111                 }
 112                 mode |= AT91_SHDW_CPTWK0_(tmp);
 113         }
 114
 115         if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
 116                         mode |= AT91_SHDW_RTCWKEN;
 117
 118         if (of_property_read_bool(np, "atmel,wakeup-rtt-timer"))
 119                         mode |= AT91_SHDW_RTTWKEN;
 120
 121         writel(wakeup_mode | mode, at91_shdwc_base + AT91_SHDW_MR);
 122 }
 123
 124 static int __init at91_poweroff_probe(struct platform_device *pdev)
 125 {
 126         struct resource *res;
 127         int ret;
 128
 129         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 130         at91_shdwc_base = devm_ioremap_resource(&pdev->dev, res);
 131         if (IS_ERR(at91_shdwc_base)) {
 132                 dev_err(&pdev->dev, "Could not map reset controller address\n");
 133                 return PTR_ERR(at91_shdwc_base);
 134         }
 135
 136         sclk = devm_clk_get(&pdev->dev, NULL);
 137         if (IS_ERR(sclk))
 138                 return PTR_ERR(sclk);
 139
 140         ret = clk_prepare_enable(sclk);
 141         if (ret) {
 142                 dev_err(&pdev->dev, "Could not enable slow clock\n");
 143                 return ret;
 144         }
 145
 146         at91_wakeup_status();
 147
 148         if (pdev->dev.of_node)
 149                 at91_poweroff_dt_set_wakeup_mode(pdev);
 150
 151         pm_power_off = at91_poweroff;
 152
 153         return 0;
 154 }
 155
 156 static int __exit at91_poweroff_remove(struct platform_device *pdev)
 157 {
 158         if (pm_power_off == at91_poweroff)
 159                 pm_power_off = NULL;
 160
 161         clk_disable_unprepare(sclk);
 162
 163         return 0;
 164 }
 165
 166 static const struct of_device_id at91_poweroff_of_match[] = {
 167         { .compatible = "atmel,at91sam9260-shdwc", },
 168         { .compatible = "atmel,at91sam9rl-shdwc", },
 169         { .compatible = "atmel,at91sam9x5-shdwc", },
 170         { /*sentinel*/ }
 171 };
 172
 173 static struct platform_driver at91_poweroff_driver = {
 174         .remove = __exit_p(at91_poweroff_remove),
 175         .driver = {
 176                 .name = "at91-poweroff",
 177                 .of_match_table = at91_poweroff_of_match,
 178         },
 179 };
 180 module_platform_driver_probe(at91_poweroff_driver, at91_poweroff_probe);
 181
 182 MODULE_AUTHOR("Atmel Corporation");
 183 MODULE_DESCRIPTION("Shutdown driver for Atmel SoCs");
 184 MODULE_LICENSE("GPL v2");