1 /* Copyright (c) 2014, The Linux Foundation. All rights reserved. 2 * 3 * This program is free software; you can redistribute it and/or modify 4 * it under the terms of the GNU General Public License version 2 and 5 * only version 2 as published by the Free Software Foundation. 6 * 7 * This program is distributed in the hope that it will be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 * GNU General Public License for more details. 11 * 12 */ 13 #include <linux/clk.h> 14 #include <linux/delay.h> 15 #include <linux/io.h> 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/of.h> 19 #include <linux/platform_device.h> 20 #include <linux/reboot.h> 21 #include <linux/watchdog.h> 22 23 #define WDT_RST 0x38 24 #define WDT_EN 0x40 25 #define WDT_BITE_TIME 0x5C 26 27 struct qcom_wdt { 28 struct watchdog_device wdd; 29 struct clk *clk; 30 unsigned long rate; 31 struct notifier_block restart_nb; 32 void __iomem *base; 33 }; 34 35 static inline 36 struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd) 37 { 38 return container_of(wdd, struct qcom_wdt, wdd); 39 } 40 41 static int qcom_wdt_start(struct watchdog_device *wdd) 42 { 43 struct qcom_wdt *wdt = to_qcom_wdt(wdd); 44 45 writel(0, wdt->base + WDT_EN); 46 writel(1, wdt->base + WDT_RST); 47 writel(wdd->timeout * wdt->rate, wdt->base + WDT_BITE_TIME); 48 writel(1, wdt->base + WDT_EN); 49 return 0; 50 } 51 52 static int qcom_wdt_stop(struct watchdog_device *wdd) 53 { 54 struct qcom_wdt *wdt = to_qcom_wdt(wdd); 55 56 writel(0, wdt->base + WDT_EN); 57 return 0; 58 } 59 60 static int qcom_wdt_ping(struct watchdog_device *wdd) 61 { 62 struct qcom_wdt *wdt = to_qcom_wdt(wdd); 63 64 writel(1, wdt->base + WDT_RST); 65 return 0; 66 } 67 68 static int qcom_wdt_set_timeout(struct watchdog_device *wdd, 69 unsigned int timeout) 70 { 71 wdd->timeout = timeout; 72 return qcom_wdt_start(wdd); 73 } 74 75 static const struct watchdog_ops qcom_wdt_ops = { 76 .start = qcom_wdt_start, 77 .stop = qcom_wdt_stop, 78 .ping = qcom_wdt_ping, 79 .set_timeout = qcom_wdt_set_timeout, 80 .owner = THIS_MODULE, 81 }; 82 83 static const struct watchdog_info qcom_wdt_info = { 84 .options = WDIOF_KEEPALIVEPING 85 | WDIOF_MAGICCLOSE 86 | WDIOF_SETTIMEOUT, 87 .identity = KBUILD_MODNAME, 88 }; 89 90 static int qcom_wdt_restart(struct notifier_block *nb, unsigned long action, 91 void *data) 92 { 93 struct qcom_wdt *wdt = container_of(nb, struct qcom_wdt, restart_nb); 94 u32 timeout; 95 96 /* 97 * Trigger watchdog bite: 98 * Setup BITE_TIME to be 128ms, and enable WDT. 99 */ 100 timeout = 128 * wdt->rate / 1000; 101 102 writel(0, wdt->base + WDT_EN); 103 writel(1, wdt->base + WDT_RST); 104 writel(timeout, wdt->base + WDT_BITE_TIME); 105 writel(1, wdt->base + WDT_EN); 106 107 /* 108 * Actually make sure the above sequence hits hardware before sleeping. 109 */ 110 wmb(); 111 112 msleep(150); 113 return NOTIFY_DONE; 114 } 115 116 static int qcom_wdt_probe(struct platform_device *pdev) 117 { 118 struct qcom_wdt *wdt; 119 struct resource *res; 120 struct device_node *np = pdev->dev.of_node; 121 u32 percpu_offset; 122 int ret; 123 124 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); 125 if (!wdt) 126 return -ENOMEM; 127 128 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 129 130 /* We use CPU0's DGT for the watchdog */ 131 if (of_property_read_u32(np, "cpu-offset", &percpu_offset)) 132 percpu_offset = 0; 133 134 res->start += percpu_offset; 135 res->end += percpu_offset; 136 137 wdt->base = devm_ioremap_resource(&pdev->dev, res); 138 if (IS_ERR(wdt->base)) 139 return PTR_ERR(wdt->base); 140 141 wdt->clk = devm_clk_get(&pdev->dev, NULL); 142 if (IS_ERR(wdt->clk)) { 143 dev_err(&pdev->dev, "failed to get input clock\n"); 144 return PTR_ERR(wdt->clk); 145 } 146 147 ret = clk_prepare_enable(wdt->clk); 148 if (ret) { 149 dev_err(&pdev->dev, "failed to setup clock\n"); 150 return ret; 151 } 152 153 /* 154 * We use the clock rate to calculate the max timeout, so ensure it's 155 * not zero to avoid a divide-by-zero exception. 156 * 157 * WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such 158 * that it would bite before a second elapses it's usefulness is 159 * limited. Bail if this is the case. 160 */ 161 wdt->rate = clk_get_rate(wdt->clk); 162 if (wdt->rate == 0 || 163 wdt->rate > 0x10000000U) { 164 dev_err(&pdev->dev, "invalid clock rate\n"); 165 ret = -EINVAL; 166 goto err_clk_unprepare; 167 } 168 169 wdt->wdd.dev = &pdev->dev; 170 wdt->wdd.info = &qcom_wdt_info; 171 wdt->wdd.ops = &qcom_wdt_ops; 172 wdt->wdd.min_timeout = 1; 173 wdt->wdd.max_timeout = 0x10000000U / wdt->rate; 174 175 /* 176 * If 'timeout-sec' unspecified in devicetree, assume a 30 second 177 * default, unless the max timeout is less than 30 seconds, then use 178 * the max instead. 179 */ 180 wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U); 181 watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); 182 183 ret = watchdog_register_device(&wdt->wdd); 184 if (ret) { 185 dev_err(&pdev->dev, "failed to register watchdog\n"); 186 goto err_clk_unprepare; 187 } 188 189 /* 190 * WDT restart notifier has priority 0 (use as a last resort) 191 */ 192 wdt->restart_nb.notifier_call = qcom_wdt_restart; 193 ret = register_restart_handler(&wdt->restart_nb); 194 if (ret) 195 dev_err(&pdev->dev, "failed to setup restart handler\n"); 196 197 platform_set_drvdata(pdev, wdt); 198 return 0; 199 200 err_clk_unprepare: 201 clk_disable_unprepare(wdt->clk); 202 return ret; 203 } 204 205 static int qcom_wdt_remove(struct platform_device *pdev) 206 { 207 struct qcom_wdt *wdt = platform_get_drvdata(pdev); 208 209 unregister_restart_handler(&wdt->restart_nb); 210 watchdog_unregister_device(&wdt->wdd); 211 clk_disable_unprepare(wdt->clk); 212 return 0; 213 } 214 215 static const struct of_device_id qcom_wdt_of_table[] = { 216 { .compatible = "qcom,kpss-timer" }, 217 { .compatible = "qcom,scss-timer" }, 218 { }, 219 }; 220 MODULE_DEVICE_TABLE(of, qcom_wdt_of_table); 221 222 static struct platform_driver qcom_watchdog_driver = { 223 .probe = qcom_wdt_probe, 224 .remove = qcom_wdt_remove, 225 .driver = { 226 .name = KBUILD_MODNAME, 227 .of_match_table = qcom_wdt_of_table, 228 }, 229 }; 230 module_platform_driver(qcom_watchdog_driver); 231 232 MODULE_DESCRIPTION("QCOM KPSS Watchdog Driver"); 233 MODULE_LICENSE("GPL v2"); 234