299 lines
7.5 KiB
C
299 lines
7.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Driver for STM32 Independent Watchdog
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*
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* Copyright (C) STMicroelectronics 2017
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* Author: Yannick Fertre <yannick.fertre@st.com> for STMicroelectronics.
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*
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* This driver is based on tegra_wdt.c
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*
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*/
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#include <linux/clk.h>
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#include <linux/delay.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/iopoll.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/watchdog.h>
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/* IWDG registers */
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#define IWDG_KR 0x00 /* Key register */
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#define IWDG_PR 0x04 /* Prescaler Register */
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#define IWDG_RLR 0x08 /* ReLoad Register */
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#define IWDG_SR 0x0C /* Status Register */
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#define IWDG_WINR 0x10 /* Windows Register */
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/* IWDG_KR register bit mask */
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#define KR_KEY_RELOAD 0xAAAA /* reload counter enable */
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#define KR_KEY_ENABLE 0xCCCC /* peripheral enable */
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#define KR_KEY_EWA 0x5555 /* write access enable */
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#define KR_KEY_DWA 0x0000 /* write access disable */
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/* IWDG_PR register */
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#define PR_SHIFT 2
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#define PR_MIN BIT(PR_SHIFT)
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/* IWDG_RLR register values */
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#define RLR_MIN 0x2 /* min value recommended */
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#define RLR_MAX GENMASK(11, 0) /* max value of reload register */
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/* IWDG_SR register bit mask */
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#define SR_PVU BIT(0) /* Watchdog prescaler value update */
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#define SR_RVU BIT(1) /* Watchdog counter reload value update */
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/* set timeout to 100000 us */
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#define TIMEOUT_US 100000
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#define SLEEP_US 1000
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struct stm32_iwdg_data {
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bool has_pclk;
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u32 max_prescaler;
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};
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static const struct stm32_iwdg_data stm32_iwdg_data = {
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.has_pclk = false,
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.max_prescaler = 256,
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};
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static const struct stm32_iwdg_data stm32mp1_iwdg_data = {
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.has_pclk = true,
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.max_prescaler = 1024,
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};
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struct stm32_iwdg {
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struct watchdog_device wdd;
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const struct stm32_iwdg_data *data;
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void __iomem *regs;
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struct clk *clk_lsi;
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struct clk *clk_pclk;
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unsigned int rate;
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};
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static inline u32 reg_read(void __iomem *base, u32 reg)
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{
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return readl_relaxed(base + reg);
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}
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static inline void reg_write(void __iomem *base, u32 reg, u32 val)
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{
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writel_relaxed(val, base + reg);
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}
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static int stm32_iwdg_start(struct watchdog_device *wdd)
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{
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struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
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u32 tout, presc, iwdg_rlr, iwdg_pr, iwdg_sr;
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int ret;
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dev_dbg(wdd->parent, "%s\n", __func__);
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tout = clamp_t(unsigned int, wdd->timeout,
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wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000);
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presc = DIV_ROUND_UP(tout * wdt->rate, RLR_MAX + 1);
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/* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */
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presc = roundup_pow_of_two(presc);
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iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT;
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iwdg_rlr = ((tout * wdt->rate) / presc) - 1;
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/* enable write access */
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reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
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/* set prescaler & reload registers */
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reg_write(wdt->regs, IWDG_PR, iwdg_pr);
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reg_write(wdt->regs, IWDG_RLR, iwdg_rlr);
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reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
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/* wait for the registers to be updated (max 100ms) */
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ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, iwdg_sr,
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!(iwdg_sr & (SR_PVU | SR_RVU)),
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SLEEP_US, TIMEOUT_US);
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if (ret) {
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dev_err(wdd->parent, "Fail to set prescaler, reload regs\n");
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return ret;
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}
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/* reload watchdog */
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reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
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return 0;
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}
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static int stm32_iwdg_ping(struct watchdog_device *wdd)
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{
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struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
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dev_dbg(wdd->parent, "%s\n", __func__);
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/* reload watchdog */
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reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
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return 0;
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}
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static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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dev_dbg(wdd->parent, "%s timeout: %d sec\n", __func__, timeout);
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wdd->timeout = timeout;
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if (watchdog_active(wdd))
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return stm32_iwdg_start(wdd);
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return 0;
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}
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static void stm32_clk_disable_unprepare(void *data)
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{
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clk_disable_unprepare(data);
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}
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static int stm32_iwdg_clk_init(struct platform_device *pdev,
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struct stm32_iwdg *wdt)
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{
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struct device *dev = &pdev->dev;
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u32 ret;
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wdt->clk_lsi = devm_clk_get(dev, "lsi");
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if (IS_ERR(wdt->clk_lsi))
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return dev_err_probe(dev, PTR_ERR(wdt->clk_lsi), "Unable to get lsi clock\n");
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/* optional peripheral clock */
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if (wdt->data->has_pclk) {
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wdt->clk_pclk = devm_clk_get(dev, "pclk");
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if (IS_ERR(wdt->clk_pclk))
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return dev_err_probe(dev, PTR_ERR(wdt->clk_pclk),
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"Unable to get pclk clock\n");
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ret = clk_prepare_enable(wdt->clk_pclk);
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if (ret) {
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dev_err(dev, "Unable to prepare pclk clock\n");
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return ret;
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}
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ret = devm_add_action_or_reset(dev,
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stm32_clk_disable_unprepare,
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wdt->clk_pclk);
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if (ret)
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return ret;
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}
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ret = clk_prepare_enable(wdt->clk_lsi);
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if (ret) {
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dev_err(dev, "Unable to prepare lsi clock\n");
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return ret;
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}
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ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare,
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wdt->clk_lsi);
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if (ret)
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return ret;
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wdt->rate = clk_get_rate(wdt->clk_lsi);
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return 0;
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}
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static const struct watchdog_info stm32_iwdg_info = {
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.options = WDIOF_SETTIMEOUT |
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WDIOF_MAGICCLOSE |
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WDIOF_KEEPALIVEPING,
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.identity = "STM32 Independent Watchdog",
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};
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static const struct watchdog_ops stm32_iwdg_ops = {
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.owner = THIS_MODULE,
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.start = stm32_iwdg_start,
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.ping = stm32_iwdg_ping,
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.set_timeout = stm32_iwdg_set_timeout,
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};
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static const struct of_device_id stm32_iwdg_of_match[] = {
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{ .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data },
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{ .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data },
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{ /* end node */ }
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};
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MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
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static int stm32_iwdg_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct watchdog_device *wdd;
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struct stm32_iwdg *wdt;
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int ret;
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wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
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if (!wdt)
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return -ENOMEM;
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wdt->data = of_device_get_match_data(&pdev->dev);
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if (!wdt->data)
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return -ENODEV;
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/* This is the timer base. */
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wdt->regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(wdt->regs))
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return PTR_ERR(wdt->regs);
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ret = stm32_iwdg_clk_init(pdev, wdt);
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if (ret)
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return ret;
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/* Initialize struct watchdog_device. */
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wdd = &wdt->wdd;
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wdd->parent = dev;
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wdd->info = &stm32_iwdg_info;
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wdd->ops = &stm32_iwdg_ops;
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wdd->min_timeout = DIV_ROUND_UP((RLR_MIN + 1) * PR_MIN, wdt->rate);
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wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler *
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1000) / wdt->rate;
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watchdog_set_drvdata(wdd, wdt);
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watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
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watchdog_init_timeout(wdd, 0, dev);
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/*
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* In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set
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* (Means U-Boot/bootloaders leaves the watchdog running)
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* When we get here we should make a decision to prevent
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* any side effects before user space daemon will take care of it.
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* The best option, taking into consideration that there is no
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* way to read values back from hardware, is to enforce watchdog
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* being run with deterministic values.
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*/
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if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) {
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ret = stm32_iwdg_start(wdd);
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if (ret)
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return ret;
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/* Make sure the watchdog is serviced */
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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}
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ret = devm_watchdog_register_device(dev, wdd);
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if (ret)
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return ret;
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platform_set_drvdata(pdev, wdt);
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return 0;
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}
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static struct platform_driver stm32_iwdg_driver = {
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.probe = stm32_iwdg_probe,
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.driver = {
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.name = "iwdg",
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.of_match_table = of_match_ptr(stm32_iwdg_of_match),
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},
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};
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module_platform_driver(stm32_iwdg_driver);
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MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
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MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver");
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MODULE_LICENSE("GPL v2");
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