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 0x0 24 #define WDT_EN 0x8 25 #define WDT_BITE_TIME 0x24 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 int ret; 121 122 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); 123 if (!wdt) 124 return -ENOMEM; 125 126 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 127 wdt->base = devm_ioremap_resource(&pdev->dev, res); 128 if (IS_ERR(wdt->base)) 129 return PTR_ERR(wdt->base); 130 131 wdt->clk = devm_clk_get(&pdev->dev, NULL); 132 if (IS_ERR(wdt->clk)) { 133 dev_err(&pdev->dev, "failed to get input clock\n"); 134 return PTR_ERR(wdt->clk); 135 } 136 137 ret = clk_prepare_enable(wdt->clk); 138 if (ret) { 139 dev_err(&pdev->dev, "failed to setup clock\n"); 140 return ret; 141 } 142 143 /* 144 * We use the clock rate to calculate the max timeout, so ensure it's 145 * not zero to avoid a divide-by-zero exception. 146 * 147 * WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such 148 * that it would bite before a second elapses it's usefulness is 149 * limited. Bail if this is the case. 150 */ 151 wdt->rate = clk_get_rate(wdt->clk); 152 if (wdt->rate == 0 || 153 wdt->rate > 0x10000000U) { 154 dev_err(&pdev->dev, "invalid clock rate\n"); 155 ret = -EINVAL; 156 goto err_clk_unprepare; 157 } 158 159 wdt->wdd.dev = &pdev->dev; 160 wdt->wdd.info = &qcom_wdt_info; 161 wdt->wdd.ops = &qcom_wdt_ops; 162 wdt->wdd.min_timeout = 1; 163 wdt->wdd.max_timeout = 0x10000000U / wdt->rate; 164 165 /* 166 * If 'timeout-sec' unspecified in devicetree, assume a 30 second 167 * default, unless the max timeout is less than 30 seconds, then use 168 * the max instead. 169 */ 170 wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U); 171 watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); 172 173 ret = watchdog_register_device(&wdt->wdd); 174 if (ret) { 175 dev_err(&pdev->dev, "failed to register watchdog\n"); 176 goto err_clk_unprepare; 177 } 178 179 /* 180 * WDT restart notifier has priority 0 (use as a last resort) 181 */ 182 wdt->restart_nb.notifier_call = qcom_wdt_restart; 183 ret = register_restart_handler(&wdt->restart_nb); 184 if (ret) 185 dev_err(&pdev->dev, "failed to setup restart handler\n"); 186 187 platform_set_drvdata(pdev, wdt); 188 return 0; 189 190 err_clk_unprepare: 191 clk_disable_unprepare(wdt->clk); 192 return ret; 193 } 194 195 static int qcom_wdt_remove(struct platform_device *pdev) 196 { 197 struct qcom_wdt *wdt = platform_get_drvdata(pdev); 198 199 unregister_restart_handler(&wdt->restart_nb); 200 watchdog_unregister_device(&wdt->wdd); 201 clk_disable_unprepare(wdt->clk); 202 return 0; 203 } 204 205 static const struct of_device_id qcom_wdt_of_table[] = { 206 { .compatible = "qcom,kpss-wdt-msm8960", }, 207 { .compatible = "qcom,kpss-wdt-apq8064", }, 208 { .compatible = "qcom,kpss-wdt-ipq8064", }, 209 { }, 210 }; 211 MODULE_DEVICE_TABLE(of, qcom_wdt_of_table); 212 213 static struct platform_driver qcom_watchdog_driver = { 214 .probe = qcom_wdt_probe, 215 .remove = qcom_wdt_remove, 216 .driver = { 217 .name = KBUILD_MODNAME, 218 .of_match_table = qcom_wdt_of_table, 219 }, 220 }; 221 module_platform_driver(qcom_watchdog_driver); 222 223 MODULE_DESCRIPTION("QCOM KPSS Watchdog Driver"); 224 MODULE_LICENSE("GPL v2"); 225