1 /* 2 * Watchdog driver for Conexant Digicolor 3 * 4 * Copyright (C) 2015 Paradox Innovation Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the 8 * Free Software Foundation; either version 2 of the License, or (at your 9 * option) any later version. 10 */ 11 12 #include <linux/types.h> 13 #include <linux/module.h> 14 #include <linux/io.h> 15 #include <linux/delay.h> 16 #include <linux/clk.h> 17 #include <linux/watchdog.h> 18 #include <linux/platform_device.h> 19 #include <linux/of_address.h> 20 21 #define TIMER_A_CONTROL 0 22 #define TIMER_A_COUNT 4 23 24 #define TIMER_A_ENABLE_COUNT BIT(0) 25 #define TIMER_A_ENABLE_WATCHDOG BIT(1) 26 27 struct dc_wdt { 28 void __iomem *base; 29 struct clk *clk; 30 spinlock_t lock; 31 }; 32 33 static unsigned timeout; 34 module_param(timeout, uint, 0); 35 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds"); 36 37 static void dc_wdt_set(struct dc_wdt *wdt, u32 ticks) 38 { 39 unsigned long flags; 40 41 spin_lock_irqsave(&wdt->lock, flags); 42 43 writel_relaxed(0, wdt->base + TIMER_A_CONTROL); 44 writel_relaxed(ticks, wdt->base + TIMER_A_COUNT); 45 writel_relaxed(TIMER_A_ENABLE_COUNT | TIMER_A_ENABLE_WATCHDOG, 46 wdt->base + TIMER_A_CONTROL); 47 48 spin_unlock_irqrestore(&wdt->lock, flags); 49 } 50 51 static int dc_wdt_restart(struct watchdog_device *wdog, unsigned long action, 52 void *data) 53 { 54 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 55 56 dc_wdt_set(wdt, 1); 57 /* wait for reset to assert... */ 58 mdelay(500); 59 60 return 0; 61 } 62 63 static int dc_wdt_start(struct watchdog_device *wdog) 64 { 65 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 66 67 dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk)); 68 69 return 0; 70 } 71 72 static int dc_wdt_stop(struct watchdog_device *wdog) 73 { 74 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 75 76 writel_relaxed(0, wdt->base + TIMER_A_CONTROL); 77 78 return 0; 79 } 80 81 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) 82 { 83 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 84 85 dc_wdt_set(wdt, t * clk_get_rate(wdt->clk)); 86 wdog->timeout = t; 87 88 return 0; 89 } 90 91 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog) 92 { 93 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 94 uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT); 95 96 return count / clk_get_rate(wdt->clk); 97 } 98 99 static struct watchdog_ops dc_wdt_ops = { 100 .owner = THIS_MODULE, 101 .start = dc_wdt_start, 102 .stop = dc_wdt_stop, 103 .set_timeout = dc_wdt_set_timeout, 104 .get_timeleft = dc_wdt_get_timeleft, 105 .restart = dc_wdt_restart, 106 }; 107 108 static struct watchdog_info dc_wdt_info = { 109 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE 110 | WDIOF_KEEPALIVEPING, 111 .identity = "Conexant Digicolor Watchdog", 112 }; 113 114 static struct watchdog_device dc_wdt_wdd = { 115 .info = &dc_wdt_info, 116 .ops = &dc_wdt_ops, 117 .min_timeout = 1, 118 }; 119 120 static int dc_wdt_probe(struct platform_device *pdev) 121 { 122 struct device *dev = &pdev->dev; 123 struct device_node *np = dev->of_node; 124 struct dc_wdt *wdt; 125 int ret; 126 127 wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL); 128 if (!wdt) 129 return -ENOMEM; 130 platform_set_drvdata(pdev, wdt); 131 132 wdt->base = of_iomap(np, 0); 133 if (!wdt->base) { 134 dev_err(dev, "Failed to remap watchdog regs"); 135 return -ENODEV; 136 } 137 138 wdt->clk = devm_clk_get(&pdev->dev, NULL); 139 if (IS_ERR(wdt->clk)) { 140 ret = PTR_ERR(wdt->clk); 141 goto err_iounmap; 142 } 143 dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk); 144 dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout; 145 dc_wdt_wdd.parent = &pdev->dev; 146 147 spin_lock_init(&wdt->lock); 148 149 watchdog_set_drvdata(&dc_wdt_wdd, wdt); 150 watchdog_set_restart_priority(&dc_wdt_wdd, 128); 151 watchdog_init_timeout(&dc_wdt_wdd, timeout, dev); 152 ret = watchdog_register_device(&dc_wdt_wdd); 153 if (ret) { 154 dev_err(dev, "Failed to register watchdog device"); 155 goto err_iounmap; 156 } 157 158 return 0; 159 160 err_iounmap: 161 iounmap(wdt->base); 162 return ret; 163 } 164 165 static int dc_wdt_remove(struct platform_device *pdev) 166 { 167 struct dc_wdt *wdt = platform_get_drvdata(pdev); 168 169 watchdog_unregister_device(&dc_wdt_wdd); 170 iounmap(wdt->base); 171 172 return 0; 173 } 174 175 static void dc_wdt_shutdown(struct platform_device *pdev) 176 { 177 dc_wdt_stop(&dc_wdt_wdd); 178 } 179 180 static const struct of_device_id dc_wdt_of_match[] = { 181 { .compatible = "cnxt,cx92755-wdt", }, 182 {}, 183 }; 184 MODULE_DEVICE_TABLE(of, dc_wdt_of_match); 185 186 static struct platform_driver dc_wdt_driver = { 187 .probe = dc_wdt_probe, 188 .remove = dc_wdt_remove, 189 .shutdown = dc_wdt_shutdown, 190 .driver = { 191 .name = "digicolor-wdt", 192 .of_match_table = dc_wdt_of_match, 193 }, 194 }; 195 module_platform_driver(dc_wdt_driver); 196 197 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); 198 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer"); 199 MODULE_LICENSE("GPL"); 200