diff options
Diffstat (limited to 'drivers/watchdog/bd96801_wdt.c')
| -rw-r--r-- | drivers/watchdog/bd96801_wdt.c | 417 |
1 files changed, 417 insertions, 0 deletions
diff --git a/drivers/watchdog/bd96801_wdt.c b/drivers/watchdog/bd96801_wdt.c new file mode 100644 index 000000000000..12b74fd2bc05 --- /dev/null +++ b/drivers/watchdog/bd96801_wdt.c @@ -0,0 +1,417 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 ROHM Semiconductors + * + * ROHM BD96801 watchdog driver + */ + +#include <linux/bitfield.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/mfd/rohm-bd96801.h> +#include <linux/mfd/rohm-generic.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reboot.h> +#include <linux/regmap.h> +#include <linux/watchdog.h> + +static bool nowayout; +module_param(nowayout, bool, 0); +MODULE_PARM_DESC(nowayout, + "Watchdog cannot be stopped once started (default=\"false\")"); + +#define BD96801_WD_TMO_SHORT_MASK 0x70 +#define BD96801_WD_RATIO_MASK 0x3 +#define BD96801_WD_TYPE_MASK 0x4 +#define BD96801_WD_TYPE_SLOW 0x4 +#define BD96801_WD_TYPE_WIN 0x0 + +#define BD96801_WD_EN_MASK 0x3 +#define BD96801_WD_IF_EN 0x1 +#define BD96801_WD_QA_EN 0x2 +#define BD96801_WD_DISABLE 0x0 + +#define BD96801_WD_ASSERT_MASK 0x8 +#define BD96801_WD_ASSERT_RST 0x8 +#define BD96801_WD_ASSERT_IRQ 0x0 + +#define BD96801_WD_FEED_MASK 0x1 +#define BD96801_WD_FEED 0x1 + +/* 1.1 mS */ +#define FASTNG_MIN 11 +#define FASTNG_MAX_US (100 * FASTNG_MIN << 7) +#define SLOWNG_MAX_US (16 * FASTNG_MAX_US) + +#define BD96801_WDT_DEFAULT_MARGIN_MS 1843 +/* Unit is seconds */ +#define DEFAULT_TIMEOUT 30 + +/* + * BD96801 WDG supports window mode so the TMO consists of SHORT and LONG + * timeout values. SHORT time is meaningful only in window mode where feeding + * period shorter than SHORT would be an error. LONG time is used to detect if + * feeding is not occurring within given time limit (SoC SW hangs). The LONG + * timeout time is a multiple of (2, 4, 8 or 16 times) the SHORT timeout. + */ + +struct wdtbd96801 { + struct device *dev; + struct regmap *regmap; + struct watchdog_device wdt; +}; + +static int bd96801_wdt_ping(struct watchdog_device *wdt) +{ + struct wdtbd96801 *w = watchdog_get_drvdata(wdt); + + return regmap_update_bits(w->regmap, BD96801_REG_WD_FEED, + BD96801_WD_FEED_MASK, BD96801_WD_FEED); +} + +static int bd96801_wdt_start(struct watchdog_device *wdt) +{ + struct wdtbd96801 *w = watchdog_get_drvdata(wdt); + + return regmap_update_bits(w->regmap, BD96801_REG_WD_CONF, + BD96801_WD_EN_MASK, BD96801_WD_IF_EN); +} + +static int bd96801_wdt_stop(struct watchdog_device *wdt) +{ + struct wdtbd96801 *w = watchdog_get_drvdata(wdt); + + return regmap_update_bits(w->regmap, BD96801_REG_WD_CONF, + BD96801_WD_EN_MASK, BD96801_WD_DISABLE); +} + +static const struct watchdog_info bd96801_wdt_info = { + .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | + WDIOF_SETTIMEOUT, + .identity = "BD96801 Watchdog", +}; + +static const struct watchdog_ops bd96801_wdt_ops = { + .start = bd96801_wdt_start, + .stop = bd96801_wdt_stop, + .ping = bd96801_wdt_ping, +}; + +static int find_closest_fast(unsigned int target, int *sel, unsigned int *val) +{ + unsigned int window = FASTNG_MIN; + int i; + + for (i = 0; i < 8 && window < target; i++) + window <<= 1; + + if (i == 8) + return -EINVAL; + + *val = window; + *sel = i; + + return 0; +} + +static int find_closest_slow_by_fast(unsigned int fast_val, unsigned int *target, + int *slowsel) +{ + static const int multipliers[] = {2, 4, 8, 16}; + int sel; + + for (sel = 0; sel < ARRAY_SIZE(multipliers) && + multipliers[sel] * fast_val < *target; sel++) + ; + + if (sel == ARRAY_SIZE(multipliers)) + return -EINVAL; + + *slowsel = sel; + *target = multipliers[sel] * fast_val; + + return 0; +} + +static int find_closest_slow(unsigned int *target, int *slow_sel, int *fast_sel) +{ + static const int multipliers[] = {2, 4, 8, 16}; + unsigned int window = FASTNG_MIN; + unsigned int val = 0; + int i, j; + + for (i = 0; i < 8; i++) { + for (j = 0; j < ARRAY_SIZE(multipliers); j++) { + unsigned int slow; + + slow = window * multipliers[j]; + if (slow >= *target && (!val || slow < val)) { + val = slow; + *fast_sel = i; + *slow_sel = j; + } + } + window <<= 1; + } + if (!val) + return -EINVAL; + + *target = val; + + return 0; +} + +static int bd96801_set_wdt_mode(struct wdtbd96801 *w, unsigned int hw_margin, + unsigned int hw_margin_min) +{ + int fastng, slowng, type, ret, reg, mask; + struct device *dev = w->dev; + + + if (hw_margin_min * 1000 > FASTNG_MAX_US) { + dev_err(dev, "Unsupported fast timeout %u uS [max %u]\n", + hw_margin_min * 1000, FASTNG_MAX_US); + + return -EINVAL; + } + + if (hw_margin * 1000 > SLOWNG_MAX_US) { + dev_err(dev, "Unsupported slow timeout %u uS [max %u]\n", + hw_margin * 1000, SLOWNG_MAX_US); + + return -EINVAL; + } + + /* + * Convert to 100uS to guarantee reasonable timeouts fit in + * 32bit maintaining also a decent accuracy. + */ + hw_margin *= 10; + hw_margin_min *= 10; + + if (hw_margin_min) { + unsigned int min; + + type = BD96801_WD_TYPE_WIN; + dev_dbg(dev, "Setting type WINDOW 0x%x\n", type); + ret = find_closest_fast(hw_margin_min, &fastng, &min); + if (ret) + return ret; + + ret = find_closest_slow_by_fast(min, &hw_margin, &slowng); + if (ret) { + dev_err(dev, + "can't support slow timeout %u uS using fast %u uS. [max slow %u uS]\n", + hw_margin * 100, min * 100, min * 100 * 16); + + return ret; + } + w->wdt.min_hw_heartbeat_ms = min / 10; + } else { + type = BD96801_WD_TYPE_SLOW; + dev_dbg(dev, "Setting type SLOW 0x%x\n", type); + ret = find_closest_slow(&hw_margin, &slowng, &fastng); + if (ret) + return ret; + } + + w->wdt.max_hw_heartbeat_ms = hw_margin / 10; + + fastng = FIELD_PREP(BD96801_WD_TMO_SHORT_MASK, fastng); + + reg = slowng | fastng; + mask = BD96801_WD_RATIO_MASK | BD96801_WD_TMO_SHORT_MASK; + ret = regmap_update_bits(w->regmap, BD96801_REG_WD_TMO, + mask, reg); + if (ret) + return ret; + + ret = regmap_update_bits(w->regmap, BD96801_REG_WD_CONF, + BD96801_WD_TYPE_MASK, type); + + return ret; +} + +static int bd96801_set_heartbeat_from_hw(struct wdtbd96801 *w, + unsigned int conf_reg) +{ + int ret; + unsigned int val, sel, fast; + + /* + * The BD96801 supports a somewhat peculiar QA-mode, which we do not + * support in this driver. If the QA-mode is enabled then we just + * warn and bail-out. + */ + if ((conf_reg & BD96801_WD_EN_MASK) != BD96801_WD_IF_EN) { + dev_err(w->dev, "watchdog set to Q&A mode - exiting\n"); + return -EINVAL; + } + + ret = regmap_read(w->regmap, BD96801_REG_WD_TMO, &val); + if (ret) + return ret; + + sel = FIELD_GET(BD96801_WD_TMO_SHORT_MASK, val); + fast = FASTNG_MIN << sel; + + sel = (val & BD96801_WD_RATIO_MASK) + 1; + w->wdt.max_hw_heartbeat_ms = (fast << sel) / USEC_PER_MSEC; + + if ((conf_reg & BD96801_WD_TYPE_MASK) == BD96801_WD_TYPE_WIN) + w->wdt.min_hw_heartbeat_ms = fast / USEC_PER_MSEC; + + return 0; +} + +static int init_wdg_hw(struct wdtbd96801 *w) +{ + u32 hw_margin[2]; + int count, ret; + u32 hw_margin_max = BD96801_WDT_DEFAULT_MARGIN_MS, hw_margin_min = 0; + + count = device_property_count_u32(w->dev->parent, "rohm,hw-timeout-ms"); + if (count < 0 && count != -EINVAL) + return count; + + if (count > 0) { + if (count > ARRAY_SIZE(hw_margin)) + return -EINVAL; + + ret = device_property_read_u32_array(w->dev->parent, + "rohm,hw-timeout-ms", + &hw_margin[0], count); + if (ret < 0) + return ret; + + if (count == 1) + hw_margin_max = hw_margin[0]; + + if (count == 2) { + if (hw_margin[1] > hw_margin[0]) { + hw_margin_max = hw_margin[1]; + hw_margin_min = hw_margin[0]; + } else { + hw_margin_max = hw_margin[0]; + hw_margin_min = hw_margin[1]; + } + } + } + + ret = bd96801_set_wdt_mode(w, hw_margin_max, hw_margin_min); + if (ret) + return ret; + + ret = device_property_match_string(w->dev->parent, "rohm,wdg-action", + "prstb"); + if (ret >= 0) { + ret = regmap_update_bits(w->regmap, BD96801_REG_WD_CONF, + BD96801_WD_ASSERT_MASK, + BD96801_WD_ASSERT_RST); + return ret; + } + + ret = device_property_match_string(w->dev->parent, "rohm,wdg-action", + "intb-only"); + if (ret >= 0) { + ret = regmap_update_bits(w->regmap, BD96801_REG_WD_CONF, + BD96801_WD_ASSERT_MASK, + BD96801_WD_ASSERT_IRQ); + return ret; + } + + return 0; +} + +static irqreturn_t bd96801_irq_hnd(int irq, void *data) +{ + emergency_restart(); + + return IRQ_NONE; +} + +static int bd96801_wdt_probe(struct platform_device *pdev) +{ + struct wdtbd96801 *w; + int ret, irq; + unsigned int val; + + w = devm_kzalloc(&pdev->dev, sizeof(*w), GFP_KERNEL); + if (!w) + return -ENOMEM; + + w->regmap = dev_get_regmap(pdev->dev.parent, NULL); + w->dev = &pdev->dev; + + w->wdt.info = &bd96801_wdt_info; + w->wdt.ops = &bd96801_wdt_ops; + w->wdt.parent = pdev->dev.parent; + w->wdt.timeout = DEFAULT_TIMEOUT; + watchdog_set_drvdata(&w->wdt, w); + + ret = regmap_read(w->regmap, BD96801_REG_WD_CONF, &val); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "Failed to get the watchdog state\n"); + + /* + * If the WDG is already enabled we assume it is configured by boot. + * In this case we just update the hw-timeout based on values set to + * the timeout / mode registers and leave the hardware configs + * untouched. + */ + if ((val & BD96801_WD_EN_MASK) != BD96801_WD_DISABLE) { + dev_dbg(&pdev->dev, "watchdog was running during probe\n"); + ret = bd96801_set_heartbeat_from_hw(w, val); + if (ret) + return ret; + + set_bit(WDOG_HW_RUNNING, &w->wdt.status); + } else { + /* If WDG is not running so we will initializate it */ + ret = init_wdg_hw(w); + if (ret) + return ret; + } + + dev_dbg(w->dev, "heartbeat set to %u - %u\n", + w->wdt.min_hw_heartbeat_ms, w->wdt.max_hw_heartbeat_ms); + + watchdog_init_timeout(&w->wdt, 0, pdev->dev.parent); + watchdog_set_nowayout(&w->wdt, nowayout); + watchdog_stop_on_reboot(&w->wdt); + + irq = platform_get_irq_byname(pdev, "bd96801-wdg"); + if (irq > 0) { + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, + bd96801_irq_hnd, + IRQF_ONESHOT, "bd96801-wdg", + NULL); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "Failed to register IRQ\n"); + } + + return devm_watchdog_register_device(&pdev->dev, &w->wdt); +} + +static const struct platform_device_id bd96801_wdt_id[] = { + { "bd96801-wdt", }, + { } +}; +MODULE_DEVICE_TABLE(platform, bd96801_wdt_id); + +static struct platform_driver bd96801_wdt = { + .driver = { + .name = "bd96801-wdt" + }, + .probe = bd96801_wdt_probe, + .id_table = bd96801_wdt_id, +}; +module_platform_driver(bd96801_wdt); + +MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>"); +MODULE_DESCRIPTION("BD96801 watchdog driver"); +MODULE_LICENSE("GPL"); |