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 return dev_err_probe(dev, PTR_ERR(wdt->clk_lsi), "Unable to get lsi clock\n"); 167 168 /* optional peripheral clock */ 169 if (wdt->data->has_pclk) { 170 wdt->clk_pclk = devm_clk_get(dev, "pclk"); 171 if (IS_ERR(wdt->clk_pclk)) 172 return dev_err_probe(dev, PTR_ERR(wdt->clk_pclk), 173 "Unable to get pclk clock\n"); 174 175 ret = clk_prepare_enable(wdt->clk_pclk); 176 if (ret) { 177 dev_err(dev, "Unable to prepare pclk clock\n"); 178 return ret; 179 } 180 ret = devm_add_action_or_reset(dev, 181 stm32_clk_disable_unprepare, 182 wdt->clk_pclk); 183 if (ret) 184 return ret; 185 } 186 187 ret = clk_prepare_enable(wdt->clk_lsi); 188 if (ret) { 189 dev_err(dev, "Unable to prepare lsi clock\n"); 190 return ret; 191 } 192 ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare, 193 wdt->clk_lsi); 194 if (ret) 195 return ret; 196 197 wdt->rate = clk_get_rate(wdt->clk_lsi); 198 199 return 0; 200 } 201 202 static const struct watchdog_info stm32_iwdg_info = { 203 .options = WDIOF_SETTIMEOUT | 204 WDIOF_MAGICCLOSE | 205 WDIOF_KEEPALIVEPING, 206 .identity = "STM32 Independent Watchdog", 207 }; 208 209 static const struct watchdog_ops stm32_iwdg_ops = { 210 .owner = THIS_MODULE, 211 .start = stm32_iwdg_start, 212 .ping = stm32_iwdg_ping, 213 .set_timeout = stm32_iwdg_set_timeout, 214 }; 215 216 static const struct of_device_id stm32_iwdg_of_match[] = { 217 { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, 218 { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, 219 { /* end node */ } 220 }; 221 MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); 222 223 static int stm32_iwdg_probe(struct platform_device *pdev) 224 { 225 struct device *dev = &pdev->dev; 226 struct watchdog_device *wdd; 227 struct stm32_iwdg *wdt; 228 int ret; 229 230 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 231 if (!wdt) 232 return -ENOMEM; 233 234 wdt->data = of_device_get_match_data(&pdev->dev); 235 if (!wdt->data) 236 return -ENODEV; 237 238 /* This is the timer base. */ 239 wdt->regs = devm_platform_ioremap_resource(pdev, 0); 240 if (IS_ERR(wdt->regs)) { 241 dev_err(dev, "Could not get resource\n"); 242 return PTR_ERR(wdt->regs); 243 } 244 245 ret = stm32_iwdg_clk_init(pdev, wdt); 246 if (ret) 247 return ret; 248 249 /* Initialize struct watchdog_device. */ 250 wdd = &wdt->wdd; 251 wdd->parent = dev; 252 wdd->info = &stm32_iwdg_info; 253 wdd->ops = &stm32_iwdg_ops; 254 wdd->min_timeout = DIV_ROUND_UP((RLR_MIN + 1) * PR_MIN, wdt->rate); 255 wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * 256 1000) / wdt->rate; 257 258 watchdog_set_drvdata(wdd, wdt); 259 watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); 260 watchdog_init_timeout(wdd, 0, dev); 261 262 /* 263 * In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set 264 * (Means U-Boot/bootloaders leaves the watchdog running) 265 * When we get here we should make a decision to prevent 266 * any side effects before user space daemon will take care of it. 267 * The best option, taking into consideration that there is no 268 * way to read values back from hardware, is to enforce watchdog 269 * being run with deterministic values. 270 */ 271 if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) { 272 ret = stm32_iwdg_start(wdd); 273 if (ret) 274 return ret; 275 276 /* Make sure the watchdog is serviced */ 277 set_bit(WDOG_HW_RUNNING, &wdd->status); 278 } 279 280 ret = devm_watchdog_register_device(dev, wdd); 281 if (ret) 282 return ret; 283 284 platform_set_drvdata(pdev, wdt); 285 286 return 0; 287 } 288 289 static struct platform_driver stm32_iwdg_driver = { 290 .probe = stm32_iwdg_probe, 291 .driver = { 292 .name = "iwdg", 293 .of_match_table = of_match_ptr(stm32_iwdg_of_match), 294 }, 295 }; 296 module_platform_driver(stm32_iwdg_driver); 297 298 MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>"); 299 MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver"); 300 MODULE_LICENSE("GPL v2"); 301