drivers/power/reset/at91-sama5d2_shdwc.c

   1 /*
   2  * Atmel SAMA5D2-Compatible Shutdown Controller (SHDWC) driver.
   3  * Found on some SoCs as the sama5d2 (obviously).
   4  *
   5  * Copyright (C) 2015 Atmel Corporation,
   6  *                    Nicolas Ferre <nicolas.ferre@atmel.com>
   7  *
   8  * Evolved from driver at91-poweroff.c.
   9  *
  10  * This file is licensed under the terms of the GNU General Public
  11  * License version 2.  This program is licensed "as is" without any
  12  * warranty of any kind, whether express or implied.
  13  *
  14  * TODO:
  15  * - addition to status of other wake-up inputs [1 - 15]
  16  * - Analog Comparator wake-up alarm
  17  * - Serial RX wake-up alarm
  18  * - low power debouncer
  19  */
  20
  21 #include <linux/clk.h>
  22 #include <linux/io.h>
  23 #include <linux/module.h>
  24 #include <linux/of.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/printk.h>
  27
  28 #define SLOW_CLOCK_FREQ 32768
  29
  30 #define AT91_SHDW_CR    0x00            /* Shut Down Control Register */
  31 #define AT91_SHDW_SHDW          BIT(0)                  /* Shut Down command */
  32 #define AT91_SHDW_KEY           (0xa5UL << 24)          /* KEY Password */
  33
  34 #define AT91_SHDW_MR    0x04            /* Shut Down Mode Register */
  35 #define AT91_SHDW_WKUPDBC_SHIFT 24
  36 #define AT91_SHDW_WKUPDBC_MASK  GENMASK(31, 16)
  37 #define AT91_SHDW_WKUPDBC(x)    (((x) << AT91_SHDW_WKUPDBC_SHIFT) \
  38                                                 & AT91_SHDW_WKUPDBC_MASK)
  39
  40 #define AT91_SHDW_SR    0x08            /* Shut Down Status Register */
  41 #define AT91_SHDW_WKUPIS_SHIFT  16
  42 #define AT91_SHDW_WKUPIS_MASK   GENMASK(31, 16)
  43 #define AT91_SHDW_WKUPIS(x)     ((1 << (x)) << AT91_SHDW_WKUPIS_SHIFT \
  44                                                 & AT91_SHDW_WKUPIS_MASK)
  45
  46 #define AT91_SHDW_WUIR  0x0c            /* Shutdown Wake-up Inputs Register */
  47 #define AT91_SHDW_WKUPEN_MASK   GENMASK(15, 0)
  48 #define AT91_SHDW_WKUPEN(x)     ((1 << (x)) & AT91_SHDW_WKUPEN_MASK)
  49 #define AT91_SHDW_WKUPT_SHIFT   16
  50 #define AT91_SHDW_WKUPT_MASK    GENMASK(31, 16)
  51 #define AT91_SHDW_WKUPT(x)      ((1 << (x)) << AT91_SHDW_WKUPT_SHIFT \
  52                                                 & AT91_SHDW_WKUPT_MASK)
  53
  54 #define SHDW_WK_PIN(reg, cfg)   ((reg) & AT91_SHDW_WKUPIS((cfg)->wkup_pin_input))
  55 #define SHDW_RTCWK(reg, cfg)    (((reg) >> ((cfg)->sr_rtcwk_shift)) & 0x1)
  56 #define SHDW_RTCWKEN(cfg)       (1 << ((cfg)->mr_rtcwk_shift))
  57
  58 #define DBC_PERIOD_US(x)        DIV_ROUND_UP_ULL((1000000 * (x)), \
  59                                                         SLOW_CLOCK_FREQ)
  60
  61 struct shdwc_config {
  62         u8 wkup_pin_input;
  63         u8 mr_rtcwk_shift;
  64         u8 sr_rtcwk_shift;
  65 };
  66
  67 struct shdwc {
  68         struct shdwc_config *cfg;
  69         void __iomem *at91_shdwc_base;
  70 };
  71
  72 /*
  73  * Hold configuration here, cannot be more than one instance of the driver
  74  * since pm_power_off itself is global.
  75  */
  76 static struct shdwc *at91_shdwc;
  77 static struct clk *sclk;
  78
  79 static const unsigned long long sdwc_dbc_period[] = {
  80         0, 3, 32, 512, 4096, 32768,
  81 };
  82
  83 static void __init at91_wakeup_status(struct platform_device *pdev)
  84 {
  85         struct shdwc *shdw = platform_get_drvdata(pdev);
  86         u32 reg;
  87         char *reason = "unknown";
  88
  89         reg = readl(shdw->at91_shdwc_base + AT91_SHDW_SR);
  90
  91         dev_dbg(&pdev->dev, "%s: status = %#x\n", __func__, reg);
  92
  93         /* Simple power-on, just bail out */
  94         if (!reg)
  95                 return;
  96
  97         if (SHDW_WK_PIN(reg, shdw->cfg))
  98                 reason = "WKUP pin";
  99         else if (SHDW_RTCWK(reg, shdw->cfg))
 100                 reason = "RTC";
 101
 102         pr_info("AT91: Wake-Up source: %s\n", reason);
 103 }
 104
 105 static void at91_poweroff(void)
 106 {
 107         writel(AT91_SHDW_KEY | AT91_SHDW_SHDW,
 108                at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);
 109 }
 110
 111 static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
 112                                       u32 in_period_us)
 113 {
 114         int i;
 115         int max_idx = ARRAY_SIZE(sdwc_dbc_period) - 1;
 116         unsigned long long period_us;
 117         unsigned long long max_period_us = DBC_PERIOD_US(sdwc_dbc_period[max_idx]);
 118
 119         if (in_period_us > max_period_us) {
 120                 dev_warn(&pdev->dev,
 121                          "debouncer period %u too big, reduced to %llu us\n",
 122                          in_period_us, max_period_us);
 123                 return max_idx;
 124         }
 125
 126         for (i = max_idx - 1; i > 0; i--) {
 127                 period_us = DBC_PERIOD_US(sdwc_dbc_period[i]);
 128                 dev_dbg(&pdev->dev, "%s: ref[%d] = %llu\n",
 129                                                 __func__, i, period_us);
 130                 if (in_period_us > period_us)
 131                         break;
 132         }
 133
 134         return i + 1;
 135 }
 136
 137 static u32 at91_shdwc_get_wakeup_input(struct platform_device *pdev,
 138                                        struct device_node *np)
 139 {
 140         struct device_node *cnp;
 141         u32 wk_input_mask;
 142         u32 wuir = 0;
 143         u32 wk_input;
 144
 145         for_each_child_of_node(np, cnp) {
 146                 if (of_property_read_u32(cnp, "reg", &wk_input)) {
 147                         dev_warn(&pdev->dev, "reg property is missing for %s\n",
 148                                  cnp->full_name);
 149                         continue;
 150                 }
 151
 152                 wk_input_mask = 1 << wk_input;
 153                 if (!(wk_input_mask & AT91_SHDW_WKUPEN_MASK)) {
 154                         dev_warn(&pdev->dev,
 155                                  "wake-up input %d out of bounds ignore\n",
 156                                  wk_input);
 157                         continue;
 158                 }
 159                 wuir |= wk_input_mask;
 160
 161                 if (of_property_read_bool(cnp, "atmel,wakeup-active-high"))
 162                         wuir |= AT91_SHDW_WKUPT(wk_input);
 163
 164                 dev_dbg(&pdev->dev, "%s: (child %d) wuir = %#x\n",
 165                                                 __func__, wk_input, wuir);
 166         }
 167
 168         return wuir;
 169 }
 170
 171 static void at91_shdwc_dt_configure(struct platform_device *pdev)
 172 {
 173         struct shdwc *shdw = platform_get_drvdata(pdev);
 174         struct device_node *np = pdev->dev.of_node;
 175         u32 mode = 0, tmp, input;
 176
 177         if (!np) {
 178                 dev_err(&pdev->dev, "device node not found\n");
 179                 return;
 180         }
 181
 182         if (!of_property_read_u32(np, "debounce-delay-us", &tmp))
 183                 mode |= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));
 184
 185         if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
 186                 mode |= SHDW_RTCWKEN(shdw->cfg);
 187
 188         dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
 189         writel(mode, shdw->at91_shdwc_base + AT91_SHDW_MR);
 190
 191         input = at91_shdwc_get_wakeup_input(pdev, np);
 192         writel(input, shdw->at91_shdwc_base + AT91_SHDW_WUIR);
 193 }
 194
 195 static const struct shdwc_config sama5d2_shdwc_config = {
 196         .wkup_pin_input = 0,
 197         .mr_rtcwk_shift = 17,
 198         .sr_rtcwk_shift = 5,
 199 };
 200
 201 static const struct of_device_id at91_shdwc_of_match[] = {
 202         {
 203                 .compatible = "atmel,sama5d2-shdwc",
 204                 .data = &sama5d2_shdwc_config,
 205         }, {
 206                 /*sentinel*/
 207         }
 208 };
 209 MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);
 210
 211 static int __init at91_shdwc_probe(struct platform_device *pdev)
 212 {
 213         struct resource *res;
 214         const struct of_device_id *match;
 215         int ret;
 216
 217         if (!pdev->dev.of_node)
 218                 return -ENODEV;
 219
 220         at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
 221         if (!at91_shdwc)
 222                 return -ENOMEM;
 223
 224         platform_set_drvdata(pdev, at91_shdwc);
 225
 226         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 227         at91_shdwc->at91_shdwc_base = devm_ioremap_resource(&pdev->dev, res);
 228         if (IS_ERR(at91_shdwc->at91_shdwc_base)) {
 229                 dev_err(&pdev->dev, "Could not map reset controller address\n");
 230                 return PTR_ERR(at91_shdwc->at91_shdwc_base);
 231         }
 232
 233         match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
 234         at91_shdwc->cfg = (struct shdwc_config *)(match->data);
 235
 236         sclk = devm_clk_get(&pdev->dev, NULL);
 237         if (IS_ERR(sclk))
 238                 return PTR_ERR(sclk);
 239
 240         ret = clk_prepare_enable(sclk);
 241         if (ret) {
 242                 dev_err(&pdev->dev, "Could not enable slow clock\n");
 243                 return ret;
 244         }
 245
 246         at91_wakeup_status(pdev);
 247
 248         at91_shdwc_dt_configure(pdev);
 249
 250         pm_power_off = at91_poweroff;
 251
 252         return 0;
 253 }
 254
 255 static int __exit at91_shdwc_remove(struct platform_device *pdev)
 256 {
 257         struct shdwc *shdw = platform_get_drvdata(pdev);
 258
 259         if (pm_power_off == at91_poweroff)
 260                 pm_power_off = NULL;
 261
 262         /* Reset values to disable wake-up features  */
 263         writel(0, shdw->at91_shdwc_base + AT91_SHDW_MR);
 264         writel(0, shdw->at91_shdwc_base + AT91_SHDW_WUIR);
 265
 266         clk_disable_unprepare(sclk);
 267
 268         return 0;
 269 }
 270
 271 static struct platform_driver at91_shdwc_driver = {
 272         .remove = __exit_p(at91_shdwc_remove),
 273         .driver = {
 274                 .name = "at91-shdwc",
 275                 .of_match_table = at91_shdwc_of_match,
 276         },
 277 };
 278 module_platform_driver_probe(at91_shdwc_driver, at91_shdwc_probe);
 279
 280 MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
 281 MODULE_DESCRIPTION("Atmel shutdown controller driver");
 282 MODULE_LICENSE("GPL v2");