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) 52 { 53 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 54 55 dc_wdt_set(wdt, 1); 56 /* wait for reset to assert... */ 57 mdelay(500); 58 59 return 0; 60 } 61 62 static int dc_wdt_start(struct watchdog_device *wdog) 63 { 64 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 65 66 dc_wdt_set(wdt, wdog->timeout * clk_get_rate(wdt->clk)); 67 68 return 0; 69 } 70 71 static int dc_wdt_stop(struct watchdog_device *wdog) 72 { 73 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 74 75 writel_relaxed(0, wdt->base + TIMER_A_CONTROL); 76 77 return 0; 78 } 79 80 static int dc_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) 81 { 82 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 83 84 dc_wdt_set(wdt, t * clk_get_rate(wdt->clk)); 85 wdog->timeout = t; 86 87 return 0; 88 } 89 90 static unsigned int dc_wdt_get_timeleft(struct watchdog_device *wdog) 91 { 92 struct dc_wdt *wdt = watchdog_get_drvdata(wdog); 93 uint32_t count = readl_relaxed(wdt->base + TIMER_A_COUNT); 94 95 return count / clk_get_rate(wdt->clk); 96 } 97 98 static struct watchdog_ops dc_wdt_ops = { 99 .owner = THIS_MODULE, 100 .start = dc_wdt_start, 101 .stop = dc_wdt_stop, 102 .set_timeout = dc_wdt_set_timeout, 103 .get_timeleft = dc_wdt_get_timeleft, 104 .restart = dc_wdt_restart, 105 }; 106 107 static struct watchdog_info dc_wdt_info = { 108 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE 109 | WDIOF_KEEPALIVEPING, 110 .identity = "Conexant Digicolor Watchdog", 111 }; 112 113 static struct watchdog_device dc_wdt_wdd = { 114 .info = &dc_wdt_info, 115 .ops = &dc_wdt_ops, 116 .min_timeout = 1, 117 }; 118 119 static int dc_wdt_probe(struct platform_device *pdev) 120 { 121 struct device *dev = &pdev->dev; 122 struct device_node *np = dev->of_node; 123 struct dc_wdt *wdt; 124 int ret; 125 126 wdt = devm_kzalloc(dev, sizeof(struct dc_wdt), GFP_KERNEL); 127 if (!wdt) 128 return -ENOMEM; 129 platform_set_drvdata(pdev, wdt); 130 131 wdt->base = of_iomap(np, 0); 132 if (!wdt->base) { 133 dev_err(dev, "Failed to remap watchdog regs"); 134 return -ENODEV; 135 } 136 137 wdt->clk = devm_clk_get(&pdev->dev, NULL); 138 if (IS_ERR(wdt->clk)) { 139 ret = PTR_ERR(wdt->clk); 140 goto err_iounmap; 141 } 142 dc_wdt_wdd.max_timeout = U32_MAX / clk_get_rate(wdt->clk); 143 dc_wdt_wdd.timeout = dc_wdt_wdd.max_timeout; 144 dc_wdt_wdd.parent = &pdev->dev; 145 146 spin_lock_init(&wdt->lock); 147 148 watchdog_set_drvdata(&dc_wdt_wdd, wdt); 149 watchdog_set_restart_priority(&dc_wdt_wdd, 128); 150 watchdog_init_timeout(&dc_wdt_wdd, timeout, dev); 151 ret = watchdog_register_device(&dc_wdt_wdd); 152 if (ret) { 153 dev_err(dev, "Failed to register watchdog device"); 154 goto err_iounmap; 155 } 156 157 return 0; 158 159 err_iounmap: 160 iounmap(wdt->base); 161 return ret; 162 } 163 164 static int dc_wdt_remove(struct platform_device *pdev) 165 { 166 struct dc_wdt *wdt = platform_get_drvdata(pdev); 167 168 watchdog_unregister_device(&dc_wdt_wdd); 169 iounmap(wdt->base); 170 171 return 0; 172 } 173 174 static void dc_wdt_shutdown(struct platform_device *pdev) 175 { 176 dc_wdt_stop(&dc_wdt_wdd); 177 } 178 179 static const struct of_device_id dc_wdt_of_match[] = { 180 { .compatible = "cnxt,cx92755-wdt", }, 181 {}, 182 }; 183 MODULE_DEVICE_TABLE(of, dc_wdt_of_match); 184 185 static struct platform_driver dc_wdt_driver = { 186 .probe = dc_wdt_probe, 187 .remove = dc_wdt_remove, 188 .shutdown = dc_wdt_shutdown, 189 .driver = { 190 .name = "digicolor-wdt", 191 .of_match_table = dc_wdt_of_match, 192 }, 193 }; 194 module_platform_driver(dc_wdt_driver); 195 196 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); 197 MODULE_DESCRIPTION("Driver for Conexant Digicolor watchdog timer"); 198 MODULE_LICENSE("GPL"); 199