Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2013 Broadcom Corporation |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public License as |
| 6 | * published by the Free Software Foundation version 2. |
| 7 | * |
| 8 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any |
| 9 | * kind, whether express or implied; without even the implied warranty |
| 10 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | * GNU General Public License for more details. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/delay.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/io.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/of_address.h> |
| 19 | #include <linux/platform_device.h> |
| 20 | #include <linux/watchdog.h> |
| 21 | |
| 22 | #define SECWDOG_CTRL_REG 0x00000000 |
| 23 | #define SECWDOG_COUNT_REG 0x00000004 |
| 24 | |
| 25 | #define SECWDOG_RESERVED_MASK 0x1dffffff |
| 26 | #define SECWDOG_WD_LOAD_FLAG 0x10000000 |
| 27 | #define SECWDOG_EN_MASK 0x08000000 |
| 28 | #define SECWDOG_SRSTEN_MASK 0x04000000 |
| 29 | #define SECWDOG_RES_MASK 0x00f00000 |
| 30 | #define SECWDOG_COUNT_MASK 0x000fffff |
| 31 | |
| 32 | #define SECWDOG_MAX_COUNT SECWDOG_COUNT_MASK |
| 33 | #define SECWDOG_CLKS_SHIFT 20 |
| 34 | #define SECWDOG_MAX_RES 15 |
| 35 | #define SECWDOG_DEFAULT_RESOLUTION 4 |
| 36 | #define SECWDOG_MAX_TRY 1000 |
| 37 | |
| 38 | #define SECS_TO_TICKS(x, w) ((x) << (w)->resolution) |
| 39 | #define TICKS_TO_SECS(x, w) ((x) >> (w)->resolution) |
| 40 | |
| 41 | #define BCM_KONA_WDT_NAME "bcm_kona_wdt" |
| 42 | |
| 43 | struct bcm_kona_wdt { |
| 44 | void __iomem *base; |
| 45 | /* |
| 46 | * One watchdog tick is 1/(2^resolution) seconds. Resolution can take |
| 47 | * the values 0-15, meaning one tick can be 1s to 30.52us. Our default |
| 48 | * resolution of 4 means one tick is 62.5ms. |
| 49 | * |
| 50 | * The watchdog counter is 20 bits. Depending on resolution, the maximum |
| 51 | * counter value of 0xfffff expires after about 12 days (resolution 0) |
| 52 | * down to only 32s (resolution 15). The default resolution of 4 gives |
| 53 | * us a maximum of about 18 hours and 12 minutes before the watchdog |
| 54 | * times out. |
| 55 | */ |
| 56 | int resolution; |
| 57 | spinlock_t lock; |
| 58 | }; |
| 59 | |
| 60 | static int secure_register_read(void __iomem *addr) |
| 61 | { |
| 62 | uint32_t val; |
| 63 | unsigned count = 0; |
| 64 | |
| 65 | /* |
| 66 | * If the WD_LOAD_FLAG is set, the watchdog counter field is being |
| 67 | * updated in hardware. Once the WD timer is updated in hardware, it |
| 68 | * gets cleared. |
| 69 | */ |
| 70 | do { |
| 71 | if (unlikely(count > 1)) |
| 72 | udelay(5); |
| 73 | val = readl_relaxed(addr); |
| 74 | count++; |
| 75 | } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); |
| 76 | |
| 77 | /* This is the only place we return a negative value. */ |
| 78 | if (val & SECWDOG_WD_LOAD_FLAG) |
| 79 | return -ETIMEDOUT; |
| 80 | |
| 81 | /* We always mask out reserved bits. */ |
| 82 | val &= SECWDOG_RESERVED_MASK; |
| 83 | |
| 84 | return val; |
| 85 | } |
| 86 | |
| 87 | static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, |
| 88 | unsigned mask, unsigned newval) |
| 89 | { |
| 90 | int val; |
| 91 | unsigned long flags; |
| 92 | int ret = 0; |
| 93 | |
| 94 | spin_lock_irqsave(&wdt->lock, flags); |
| 95 | |
| 96 | val = secure_register_read(wdt->base + SECWDOG_CTRL_REG); |
| 97 | if (val < 0) { |
| 98 | ret = val; |
| 99 | } else { |
| 100 | val &= ~mask; |
| 101 | val |= newval; |
| 102 | writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); |
| 103 | } |
| 104 | |
| 105 | spin_unlock_irqrestore(&wdt->lock, flags); |
| 106 | |
| 107 | return ret; |
| 108 | } |
| 109 | |
| 110 | static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) |
| 111 | { |
| 112 | if (wdt->resolution > SECWDOG_MAX_RES) |
| 113 | return -EINVAL; |
| 114 | |
| 115 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, |
| 116 | wdt->resolution << SECWDOG_CLKS_SHIFT); |
| 117 | } |
| 118 | |
| 119 | static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, |
| 120 | unsigned watchdog_flags) |
| 121 | { |
| 122 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); |
| 123 | |
| 124 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, |
| 125 | SECS_TO_TICKS(wdog->timeout, wdt) | |
| 126 | watchdog_flags); |
| 127 | } |
| 128 | |
| 129 | static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, |
| 130 | unsigned int t) |
| 131 | { |
| 132 | wdog->timeout = t; |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) |
| 137 | { |
| 138 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); |
| 139 | int val; |
| 140 | unsigned long flags; |
| 141 | |
| 142 | spin_lock_irqsave(&wdt->lock, flags); |
| 143 | val = secure_register_read(wdt->base + SECWDOG_COUNT_REG); |
| 144 | spin_unlock_irqrestore(&wdt->lock, flags); |
| 145 | |
| 146 | if (val < 0) |
| 147 | return val; |
| 148 | |
| 149 | return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); |
| 150 | } |
| 151 | |
| 152 | static int bcm_kona_wdt_start(struct watchdog_device *wdog) |
| 153 | { |
| 154 | return bcm_kona_wdt_set_timeout_reg(wdog, |
| 155 | SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); |
| 156 | } |
| 157 | |
| 158 | static int bcm_kona_wdt_stop(struct watchdog_device *wdog) |
| 159 | { |
| 160 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); |
| 161 | |
| 162 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | |
| 163 | SECWDOG_SRSTEN_MASK, 0); |
| 164 | } |
| 165 | |
| 166 | static struct watchdog_ops bcm_kona_wdt_ops = { |
| 167 | .owner = THIS_MODULE, |
| 168 | .start = bcm_kona_wdt_start, |
| 169 | .stop = bcm_kona_wdt_stop, |
| 170 | .set_timeout = bcm_kona_wdt_set_timeout, |
| 171 | .get_timeleft = bcm_kona_wdt_get_timeleft, |
| 172 | }; |
| 173 | |
| 174 | static struct watchdog_info bcm_kona_wdt_info = { |
| 175 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | |
| 176 | WDIOF_KEEPALIVEPING, |
| 177 | .identity = "Broadcom Kona Watchdog Timer", |
| 178 | }; |
| 179 | |
| 180 | static struct watchdog_device bcm_kona_wdt_wdd = { |
| 181 | .info = &bcm_kona_wdt_info, |
| 182 | .ops = &bcm_kona_wdt_ops, |
| 183 | .min_timeout = 1, |
| 184 | .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, |
| 185 | .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, |
| 186 | }; |
| 187 | |
| 188 | static void bcm_kona_wdt_shutdown(struct platform_device *pdev) |
| 189 | { |
| 190 | bcm_kona_wdt_stop(&bcm_kona_wdt_wdd); |
| 191 | } |
| 192 | |
| 193 | static int bcm_kona_wdt_probe(struct platform_device *pdev) |
| 194 | { |
| 195 | struct device *dev = &pdev->dev; |
| 196 | struct bcm_kona_wdt *wdt; |
| 197 | struct resource *res; |
| 198 | int ret; |
| 199 | |
| 200 | wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); |
| 201 | if (!wdt) |
| 202 | return -ENOMEM; |
| 203 | |
| 204 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 205 | wdt->base = devm_ioremap_resource(dev, res); |
| 206 | if (IS_ERR(wdt->base)) |
| 207 | return -ENODEV; |
| 208 | |
| 209 | wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; |
| 210 | ret = bcm_kona_wdt_set_resolution_reg(wdt); |
| 211 | if (ret) { |
| 212 | dev_err(dev, "Failed to set resolution (error: %d)", ret); |
| 213 | return ret; |
| 214 | } |
| 215 | |
| 216 | spin_lock_init(&wdt->lock); |
| 217 | platform_set_drvdata(pdev, wdt); |
| 218 | watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); |
| 219 | |
| 220 | ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); |
| 221 | if (ret) { |
| 222 | dev_err(dev, "Failed set watchdog timeout"); |
| 223 | return ret; |
| 224 | } |
| 225 | |
| 226 | ret = watchdog_register_device(&bcm_kona_wdt_wdd); |
| 227 | if (ret) { |
| 228 | dev_err(dev, "Failed to register watchdog device"); |
| 229 | return ret; |
| 230 | } |
| 231 | |
| 232 | dev_dbg(dev, "Broadcom Kona Watchdog Timer"); |
| 233 | |
| 234 | return 0; |
| 235 | } |
| 236 | |
| 237 | static int bcm_kona_wdt_remove(struct platform_device *pdev) |
| 238 | { |
| 239 | bcm_kona_wdt_shutdown(pdev); |
| 240 | watchdog_unregister_device(&bcm_kona_wdt_wdd); |
| 241 | dev_dbg(&pdev->dev, "Watchdog driver disabled"); |
| 242 | |
| 243 | return 0; |
| 244 | } |
| 245 | |
| 246 | static const struct of_device_id bcm_kona_wdt_of_match[] = { |
| 247 | { .compatible = "brcm,kona-wdt", }, |
| 248 | {}, |
| 249 | }; |
| 250 | MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); |
| 251 | |
| 252 | static struct platform_driver bcm_kona_wdt_driver = { |
| 253 | .driver = { |
| 254 | .name = BCM_KONA_WDT_NAME, |
| 255 | .owner = THIS_MODULE, |
| 256 | .of_match_table = bcm_kona_wdt_of_match, |
| 257 | }, |
| 258 | .probe = bcm_kona_wdt_probe, |
| 259 | .remove = bcm_kona_wdt_remove, |
| 260 | .shutdown = bcm_kona_wdt_shutdown, |
| 261 | }; |
| 262 | |
| 263 | module_platform_driver(bcm_kona_wdt_driver); |
| 264 | |
| 265 | MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); |
| 266 | MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); |
| 267 | MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); |
| 268 | MODULE_LICENSE("GPL v2"); |