292 lines
6.7 KiB
C
292 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2020 ROHM Semiconductors
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*
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* ROHM BD9576MUF and BD9573MUF Watchdog driver
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*/
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/mfd/rohm-bd957x.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/watchdog.h>
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static bool nowayout;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default=\"false\")");
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#define HW_MARGIN_MIN 2
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#define HW_MARGIN_MAX 4416
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#define BD957X_WDT_DEFAULT_MARGIN 4416
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#define WATCHDOG_TIMEOUT 30
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struct bd9576_wdt_priv {
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struct gpio_desc *gpiod_ping;
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struct gpio_desc *gpiod_en;
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struct device *dev;
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struct regmap *regmap;
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bool always_running;
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struct watchdog_device wdd;
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};
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static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
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{
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gpiod_set_value_cansleep(priv->gpiod_en, 0);
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}
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static int bd9576_wdt_ping(struct watchdog_device *wdd)
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{
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struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
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/* Pulse */
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gpiod_set_value_cansleep(priv->gpiod_ping, 1);
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gpiod_set_value_cansleep(priv->gpiod_ping, 0);
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return 0;
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}
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static int bd9576_wdt_start(struct watchdog_device *wdd)
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{
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struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
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gpiod_set_value_cansleep(priv->gpiod_en, 1);
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return bd9576_wdt_ping(wdd);
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}
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static int bd9576_wdt_stop(struct watchdog_device *wdd)
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{
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struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
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if (!priv->always_running)
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bd9576_wdt_disable(priv);
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else
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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return 0;
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}
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static const struct watchdog_info bd957x_wdt_ident = {
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.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
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WDIOF_SETTIMEOUT,
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.identity = "BD957x Watchdog",
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};
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static const struct watchdog_ops bd957x_wdt_ops = {
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.owner = THIS_MODULE,
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.start = bd9576_wdt_start,
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.stop = bd9576_wdt_stop,
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.ping = bd9576_wdt_ping,
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};
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/* Unit is hundreds of uS */
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#define FASTNG_MIN 23
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static int find_closest_fast(int target, int *sel, int *val)
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{
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int i;
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int window = FASTNG_MIN;
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for (i = 0; i < 8 && window < target; i++)
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window <<= 1;
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*val = window;
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*sel = i;
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if (i == 8)
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return -EINVAL;
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return 0;
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}
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static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
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{
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int sel;
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static const int multipliers[] = {2, 3, 7, 15};
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for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
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multipliers[sel] * fast_val < target; sel++)
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;
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if (sel == ARRAY_SIZE(multipliers))
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return -EINVAL;
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*slowsel = sel;
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return 0;
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}
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static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
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{
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static const int multipliers[] = {2, 3, 7, 15};
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int i, j;
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int val = 0;
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int window = FASTNG_MIN;
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for (i = 0; i < 8; i++) {
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for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
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int slow;
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slow = window * multipliers[j];
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if (slow >= target && (!val || slow < val)) {
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val = slow;
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*fast_sel = i;
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*slow_sel = j;
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}
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}
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window <<= 1;
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}
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if (!val)
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return -EINVAL;
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return 0;
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}
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#define BD957X_WDG_TYPE_WINDOW BIT(5)
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#define BD957X_WDG_TYPE_SLOW 0
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#define BD957X_WDG_TYPE_MASK BIT(5)
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#define BD957X_WDG_NG_RATIO_MASK 0x18
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#define BD957X_WDG_FASTNG_MASK 0x7
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static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
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int hw_margin_min)
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{
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int ret, fastng, slowng, type, reg, mask;
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struct device *dev = priv->dev;
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/* convert to 100uS */
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hw_margin *= 10;
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hw_margin_min *= 10;
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if (hw_margin_min) {
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int min;
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type = BD957X_WDG_TYPE_WINDOW;
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dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
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ret = find_closest_fast(hw_margin_min, &fastng, &min);
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if (ret) {
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dev_err(dev, "bad WDT window for fast timeout\n");
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return ret;
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}
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ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
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if (ret) {
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dev_err(dev, "bad WDT window\n");
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return ret;
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}
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} else {
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type = BD957X_WDG_TYPE_SLOW;
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dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
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ret = find_closest_slow(hw_margin, &slowng, &fastng);
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if (ret) {
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dev_err(dev, "bad WDT window\n");
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return ret;
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}
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}
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slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
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reg = type | slowng | fastng;
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mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
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BD957X_WDG_FASTNG_MASK;
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ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
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mask, reg);
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return ret;
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}
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static int bd9576_wdt_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->parent->of_node;
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struct bd9576_wdt_priv *priv;
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u32 hw_margin[2];
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u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
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int ret;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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platform_set_drvdata(pdev, priv);
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priv->dev = dev;
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priv->regmap = dev_get_regmap(dev->parent, NULL);
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if (!priv->regmap) {
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dev_err(dev, "No regmap found\n");
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return -ENODEV;
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}
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priv->gpiod_en = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
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"rohm,watchdog-enable-gpios",
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0, GPIOD_OUT_LOW,
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"watchdog-enable");
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if (IS_ERR(priv->gpiod_en))
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return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
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"getting watchdog-enable GPIO failed\n");
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priv->gpiod_ping = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
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"rohm,watchdog-ping-gpios",
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0, GPIOD_OUT_LOW,
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"watchdog-ping");
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if (IS_ERR(priv->gpiod_ping))
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return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
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"getting watchdog-ping GPIO failed\n");
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ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-ms",
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&hw_margin[0], 1, 2);
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if (ret < 0 && ret != -EINVAL)
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return ret;
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if (ret == 1)
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hw_margin_max = hw_margin[0];
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if (ret == 2) {
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hw_margin_max = hw_margin[1];
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hw_margin_min = hw_margin[0];
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}
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ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
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if (ret)
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return ret;
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priv->always_running = of_property_read_bool(np, "always-running");
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watchdog_set_drvdata(&priv->wdd, priv);
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priv->wdd.info = &bd957x_wdt_ident;
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priv->wdd.ops = &bd957x_wdt_ops;
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priv->wdd.min_hw_heartbeat_ms = hw_margin_min;
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priv->wdd.max_hw_heartbeat_ms = hw_margin_max;
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priv->wdd.parent = dev;
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priv->wdd.timeout = WATCHDOG_TIMEOUT;
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watchdog_init_timeout(&priv->wdd, 0, dev);
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watchdog_set_nowayout(&priv->wdd, nowayout);
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watchdog_stop_on_reboot(&priv->wdd);
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if (priv->always_running)
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bd9576_wdt_start(&priv->wdd);
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return devm_watchdog_register_device(dev, &priv->wdd);
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}
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static struct platform_driver bd9576_wdt_driver = {
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.driver = {
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.name = "bd9576-wdt",
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},
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.probe = bd9576_wdt_probe,
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};
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module_platform_driver(bd9576_wdt_driver);
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MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
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MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:bd9576-wdt");
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