1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Driver for STM32 Independent Watchdog 4 * 5 * Copyright (C) STMicroelectronics 2017 6 * Author: Yannick Fertre <yannick.fertre@st.com> for STMicroelectronics. 7 * 8 * This driver is based on tegra_wdt.c 9 * 10 */ 11 12 #include <linux/clk.h> 13 #include <linux/delay.h> 14 #include <linux/interrupt.h> 15 #include <linux/io.h> 16 #include <linux/iopoll.h> 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/of_device.h> 21 #include <linux/platform_device.h> 22 #include <linux/watchdog.h> 23 24 /* IWDG registers */ 25 #define IWDG_KR 0x00 /* Key register */ 26 #define IWDG_PR 0x04 /* Prescaler Register */ 27 #define IWDG_RLR 0x08 /* ReLoad Register */ 28 #define IWDG_SR 0x0C /* Status Register */ 29 #define IWDG_WINR 0x10 /* Windows Register */ 30 31 /* IWDG_KR register bit mask */ 32 #define KR_KEY_RELOAD 0xAAAA /* reload counter enable */ 33 #define KR_KEY_ENABLE 0xCCCC /* peripheral enable */ 34 #define KR_KEY_EWA 0x5555 /* write access enable */ 35 #define KR_KEY_DWA 0x0000 /* write access disable */ 36 37 /* IWDG_PR register */ 38 #define PR_SHIFT 2 39 #define PR_MIN BIT(PR_SHIFT) 40 41 /* IWDG_RLR register values */ 42 #define RLR_MIN 0x2 /* min value recommended */ 43 #define RLR_MAX GENMASK(11, 0) /* max value of reload register */ 44 45 /* IWDG_SR register bit mask */ 46 #define SR_PVU BIT(0) /* Watchdog prescaler value update */ 47 #define SR_RVU BIT(1) /* Watchdog counter reload value update */ 48 49 /* set timeout to 100000 us */ 50 #define TIMEOUT_US 100000 51 #define SLEEP_US 1000 52 53 struct stm32_iwdg_data { 54 bool has_pclk; 55 u32 max_prescaler; 56 }; 57 58 static const struct stm32_iwdg_data stm32_iwdg_data = { 59 .has_pclk = false, 60 .max_prescaler = 256, 61 }; 62 63 static const struct stm32_iwdg_data stm32mp1_iwdg_data = { 64 .has_pclk = true, 65 .max_prescaler = 1024, 66 }; 67 68 struct stm32_iwdg { 69 struct watchdog_device wdd; 70 const struct stm32_iwdg_data *data; 71 void __iomem *regs; 72 struct clk *clk_lsi; 73 struct clk *clk_pclk; 74 unsigned int rate; 75 }; 76 77 static inline u32 reg_read(void __iomem *base, u32 reg) 78 { 79 return readl_relaxed(base + reg); 80 } 81 82 static inline void reg_write(void __iomem *base, u32 reg, u32 val) 83 { 84 writel_relaxed(val, base + reg); 85 } 86 87 static int stm32_iwdg_start(struct watchdog_device *wdd) 88 { 89 struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); 90 u32 tout, presc, iwdg_rlr, iwdg_pr, iwdg_sr; 91 int ret; 92 93 dev_dbg(wdd->parent, "%s\n", __func__); 94 95 tout = clamp_t(unsigned int, wdd->timeout, 96 wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); 97 98 presc = DIV_ROUND_UP(tout * wdt->rate, RLR_MAX + 1); 99 100 /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ 101 presc = roundup_pow_of_two(presc); 102 iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; 103 iwdg_rlr = ((tout * wdt->rate) / presc) - 1; 104 105 /* enable write access */ 106 reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); 107 108 /* set prescaler & reload registers */ 109 reg_write(wdt->regs, IWDG_PR, iwdg_pr); 110 reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); 111 reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); 112 113 /* wait for the registers to be updated (max 100ms) */ 114 ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, iwdg_sr, 115 !(iwdg_sr & (SR_PVU | SR_RVU)), 116 SLEEP_US, TIMEOUT_US); 117 if (ret) { 118 dev_err(wdd->parent, "Fail to set prescaler, reload regs\n"); 119 return ret; 120 } 121 122 /* reload watchdog */ 123 reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); 124 125 return 0; 126 } 127 128 static int stm32_iwdg_ping(struct watchdog_device *wdd) 129 { 130 struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); 131 132 dev_dbg(wdd->parent, "%s\n", __func__); 133 134 /* reload watchdog */ 135 reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); 136 137 return 0; 138 } 139 140 static int stm32_iwdg_set_timeout(struct watchdog_device *wdd, 141 unsigned int timeout) 142 { 143 dev_dbg(wdd->parent, "%s timeout: %d sec\n", __func__, timeout); 144 145 wdd->timeout = timeout; 146 147 if (watchdog_active(wdd)) 148 return stm32_iwdg_start(wdd); 149 150 return 0; 151 } 152 153 static void stm32_clk_disable_unprepare(void *data) 154 { 155 clk_disable_unprepare(data); 156 } 157 158 static int stm32_iwdg_clk_init(struct platform_device *pdev, 159 struct stm32_iwdg *wdt) 160 { 161 struct device *dev = &pdev->dev; 162 u32 ret; 163 164 wdt->clk_lsi = devm_clk_get(dev, "lsi"); 165 if (IS_ERR(wdt->clk_lsi)) { 166 dev_err(dev, "Unable to get lsi clock\n"); 167 return PTR_ERR(wdt->clk_lsi); 168 } 169 170 /* optional peripheral clock */ 171 if (wdt->data->has_pclk) { 172 wdt->clk_pclk = devm_clk_get(dev, "pclk"); 173 if (IS_ERR(wdt->clk_pclk)) { 174 dev_err(dev, "Unable to get pclk clock\n"); 175 return PTR_ERR(wdt->clk_pclk); 176 } 177 178 ret = clk_prepare_enable(wdt->clk_pclk); 179 if (ret) { 180 dev_err(dev, "Unable to prepare pclk clock\n"); 181 return ret; 182 } 183 ret = devm_add_action_or_reset(dev, 184 stm32_clk_disable_unprepare, 185 wdt->clk_pclk); 186 if (ret) 187 return ret; 188 } 189 190 ret = clk_prepare_enable(wdt->clk_lsi); 191 if (ret) { 192 dev_err(dev, "Unable to prepare lsi clock\n"); 193 return ret; 194 } 195 ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare, 196 wdt->clk_lsi); 197 if (ret) 198 return ret; 199 200 wdt->rate = clk_get_rate(wdt->clk_lsi); 201 202 return 0; 203 } 204 205 static const struct watchdog_info stm32_iwdg_info = { 206 .options = WDIOF_SETTIMEOUT | 207 WDIOF_MAGICCLOSE | 208 WDIOF_KEEPALIVEPING, 209 .identity = "STM32 Independent Watchdog", 210 }; 211 212 static const struct watchdog_ops stm32_iwdg_ops = { 213 .owner = THIS_MODULE, 214 .start = stm32_iwdg_start, 215 .ping = stm32_iwdg_ping, 216 .set_timeout = stm32_iwdg_set_timeout, 217 }; 218 219 static const struct of_device_id stm32_iwdg_of_match[] = { 220 { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, 221 { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, 222 { /* end node */ } 223 }; 224 MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); 225 226 static int stm32_iwdg_probe(struct platform_device *pdev) 227 { 228 struct device *dev = &pdev->dev; 229 struct watchdog_device *wdd; 230 struct stm32_iwdg *wdt; 231 int ret; 232 233 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 234 if (!wdt) 235 return -ENOMEM; 236 237 wdt->data = of_device_get_match_data(&pdev->dev); 238 if (!wdt->data) 239 return -ENODEV; 240 241 /* This is the timer base. */ 242 wdt->regs = devm_platform_ioremap_resource(pdev, 0); 243 if (IS_ERR(wdt->regs)) { 244 dev_err(dev, "Could not get resource\n"); 245 return PTR_ERR(wdt->regs); 246 } 247 248 ret = stm32_iwdg_clk_init(pdev, wdt); 249 if (ret) 250 return ret; 251 252 /* Initialize struct watchdog_device. */ 253 wdd = &wdt->wdd; 254 wdd->parent = dev; 255 wdd->info = &stm32_iwdg_info; 256 wdd->ops = &stm32_iwdg_ops; 257 wdd->min_timeout = DIV_ROUND_UP((RLR_MIN + 1) * PR_MIN, wdt->rate); 258 wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * 259 1000) / wdt->rate; 260 261 watchdog_set_drvdata(wdd, wdt); 262 watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); 263 watchdog_init_timeout(wdd, 0, dev); 264 265 /* 266 * In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set 267 * (Means U-Boot/bootloaders leaves the watchdog running) 268 * When we get here we should make a decision to prevent 269 * any side effects before user space daemon will take care of it. 270 * The best option, taking into consideration that there is no 271 * way to read values back from hardware, is to enforce watchdog 272 * being run with deterministic values. 273 */ 274 if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) { 275 ret = stm32_iwdg_start(wdd); 276 if (ret) 277 return ret; 278 279 /* Make sure the watchdog is serviced */ 280 set_bit(WDOG_HW_RUNNING, &wdd->status); 281 } 282 283 ret = devm_watchdog_register_device(dev, wdd); 284 if (ret) 285 return ret; 286 287 platform_set_drvdata(pdev, wdt); 288 289 return 0; 290 } 291 292 static struct platform_driver stm32_iwdg_driver = { 293 .probe = stm32_iwdg_probe, 294 .driver = { 295 .name = "iwdg", 296 .of_match_table = of_match_ptr(stm32_iwdg_of_match), 297 }, 298 }; 299 module_platform_driver(stm32_iwdg_driver); 300 301 MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>"); 302 MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver"); 303 MODULE_LICENSE("GPL v2"); 304