| 1 | /* |
| 2 | * Moschip MCS814x Watchdog driver |
| 3 | * |
| 4 | * Copyright (C) 2012, Florian Fainelli <florian@openwrt.org> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License as published by |
| 8 | * the Free Software Foundation; either version 2 of the License, or |
| 9 | * (at your option) any later version. |
| 10 | * |
| 11 | * This program is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | * GNU General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License |
| 17 | * along with this program; if not, write to the Free Software |
| 18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 19 | */ |
| 20 | |
| 21 | #include <linux/module.h> |
| 22 | #include <linux/slab.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/platform_device.h> |
| 25 | #include <linux/miscdevice.h> |
| 26 | #include <linux/watchdog.h> |
| 27 | #include <linux/io.h> |
| 28 | #include <linux/err.h> |
| 29 | #include <linux/clk.h> |
| 30 | #include <linux/of.h> |
| 31 | |
| 32 | #define WDT_COUNT 0x00 |
| 33 | #define WDT_CTRL 0x04 |
| 34 | #define WDT_CTRL_EN 0x1 |
| 35 | |
| 36 | /* watchdog frequency */ |
| 37 | #define WDT_MAX_VALUE (0xffffffff) |
| 38 | |
| 39 | struct mcs814x_wdt { |
| 40 | void __iomem *regs; |
| 41 | spinlock_t lock; |
| 42 | struct watchdog_device wdt_dev; |
| 43 | struct clk *clk; |
| 44 | }; |
| 45 | |
| 46 | static int mcs814x_wdt_start(struct watchdog_device *dev) |
| 47 | { |
| 48 | struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev); |
| 49 | u32 reg; |
| 50 | |
| 51 | spin_lock(&wdt->lock); |
| 52 | reg = readl_relaxed(wdt->regs + WDT_CTRL); |
| 53 | reg |= WDT_CTRL_EN; |
| 54 | writel_relaxed(reg, wdt->regs + WDT_CTRL); |
| 55 | spin_unlock(&wdt->lock); |
| 56 | |
| 57 | return 0; |
| 58 | } |
| 59 | |
| 60 | static int mcs814x_wdt_stop(struct watchdog_device *dev) |
| 61 | { |
| 62 | struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev); |
| 63 | u32 reg; |
| 64 | |
| 65 | spin_lock(&wdt->lock); |
| 66 | reg = readl_relaxed(wdt->regs + WDT_CTRL); |
| 67 | reg &= ~WDT_CTRL_EN; |
| 68 | writel_relaxed(reg, wdt->regs + WDT_CTRL); |
| 69 | spin_unlock(&wdt->lock); |
| 70 | |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | static int mcs814x_wdt_set_timeout(struct watchdog_device *dev, |
| 75 | unsigned int new_timeout) |
| 76 | { |
| 77 | struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev); |
| 78 | |
| 79 | spin_lock(&wdt->lock); |
| 80 | /* watchdog counts upward and rollover (0xfffffff -> 0) |
| 81 | * triggers the reboot |
| 82 | */ |
| 83 | writel_relaxed(WDT_MAX_VALUE - (new_timeout * clk_get_rate(wdt->clk)), |
| 84 | wdt->regs + WDT_COUNT); |
| 85 | spin_unlock(&wdt->lock); |
| 86 | |
| 87 | return 0; |
| 88 | } |
| 89 | |
| 90 | static int mcs814x_wdt_ping(struct watchdog_device *dev) |
| 91 | { |
| 92 | /* restart the watchdog */ |
| 93 | mcs814x_wdt_stop(dev); |
| 94 | mcs814x_wdt_set_timeout(dev, dev->timeout); |
| 95 | mcs814x_wdt_start(dev); |
| 96 | |
| 97 | return 0; |
| 98 | } |
| 99 | |
| 100 | static const struct watchdog_info mcs814x_wdt_ident = { |
| 101 | .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | |
| 102 | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, |
| 103 | .identity = "MCS814x Watchdog", |
| 104 | }; |
| 105 | |
| 106 | static struct watchdog_ops mcs814x_wdt_ops = { |
| 107 | .owner = THIS_MODULE, |
| 108 | .start = mcs814x_wdt_start, |
| 109 | .stop = mcs814x_wdt_stop, |
| 110 | .set_timeout = mcs814x_wdt_set_timeout, |
| 111 | .ping = mcs814x_wdt_ping, |
| 112 | }; |
| 113 | |
| 114 | static int __devinit mcs814x_wdt_probe(struct platform_device *pdev) |
| 115 | { |
| 116 | struct resource *res; |
| 117 | struct mcs814x_wdt *wdt; |
| 118 | int ret; |
| 119 | struct clk *clk; |
| 120 | |
| 121 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 122 | if (!res) |
| 123 | return -ENODEV; |
| 124 | |
| 125 | clk = clk_get(NULL, "wdt"); |
| 126 | if (IS_ERR_OR_NULL(clk)) { |
| 127 | dev_err(&pdev->dev, "failed to get watchdog clock\n"); |
| 128 | return PTR_ERR(clk); |
| 129 | } |
| 130 | |
| 131 | wdt = kzalloc(sizeof(*wdt), GFP_KERNEL); |
| 132 | if (!wdt) { |
| 133 | ret = -ENOMEM; |
| 134 | goto out_clk; |
| 135 | } |
| 136 | |
| 137 | spin_lock_init(&wdt->lock); |
| 138 | wdt->clk = clk; |
| 139 | wdt->wdt_dev.info = &mcs814x_wdt_ident; |
| 140 | wdt->wdt_dev.ops = &mcs814x_wdt_ops; |
| 141 | wdt->wdt_dev.min_timeout = 1; |
| 142 | /* approximately 10995 secs */ |
| 143 | wdt->wdt_dev.max_timeout = (WDT_MAX_VALUE / clk_get_rate(clk)); |
| 144 | |
| 145 | platform_set_drvdata(pdev, wdt); |
| 146 | |
| 147 | /* only ioremap registers, because the register is shared */ |
| 148 | wdt->regs = devm_ioremap(&pdev->dev, res->start, resource_size(res)); |
| 149 | if (!wdt->regs) { |
| 150 | ret = -ENOMEM; |
| 151 | goto out; |
| 152 | } |
| 153 | |
| 154 | watchdog_set_drvdata(&wdt->wdt_dev, wdt); |
| 155 | |
| 156 | ret = watchdog_register_device(&wdt->wdt_dev); |
| 157 | if (ret) { |
| 158 | dev_err(&pdev->dev, "cannot register watchdog: %d\n", ret); |
| 159 | goto out; |
| 160 | } |
| 161 | |
| 162 | dev_info(&pdev->dev, "registered\n"); |
| 163 | return 0; |
| 164 | |
| 165 | out: |
| 166 | platform_set_drvdata(pdev, NULL); |
| 167 | kfree(wdt); |
| 168 | out_clk: |
| 169 | clk_put(clk); |
| 170 | return ret; |
| 171 | } |
| 172 | |
| 173 | static int __devexit mcs814x_wdt_remove(struct platform_device *pdev) |
| 174 | { |
| 175 | struct mcs814x_wdt *wdt = platform_get_drvdata(pdev); |
| 176 | |
| 177 | clk_put(wdt->clk); |
| 178 | watchdog_unregister_device(&wdt->wdt_dev); |
| 179 | watchdog_set_drvdata(&wdt->wdt_dev, NULL); |
| 180 | kfree(wdt); |
| 181 | platform_set_drvdata(pdev, NULL); |
| 182 | |
| 183 | return 0; |
| 184 | } |
| 185 | |
| 186 | static const struct of_device_id mcs814x_wdt_ids[] = { |
| 187 | { .compatible = "moschip,mcs814x-wdt", }, |
| 188 | { /* sentinel */ }, |
| 189 | }; |
| 190 | |
| 191 | static struct platform_driver mcs814x_wdt_driver = { |
| 192 | .driver = { |
| 193 | .name = "mcs814x-wdt", |
| 194 | .owner = THIS_MODULE, |
| 195 | .of_match_table = mcs814x_wdt_ids, |
| 196 | }, |
| 197 | .probe = mcs814x_wdt_probe, |
| 198 | .remove = __devexit_p(mcs814x_wdt_remove), |
| 199 | }; |
| 200 | |
| 201 | module_platform_driver(mcs814x_wdt_driver); |
| 202 | |
| 203 | MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>"); |
| 204 | MODULE_DESCRIPTION("Moschip MCS814x Watchdog driver"); |
| 205 | MODULE_LICENSE("GPL"); |
| 206 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
| 207 | MODULE_ALIAS("platform:mcs814x-wdt"); |
| 208 | |
