--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/V2H(P) WDT Watchdog Driver
+ *
+ * Copyright (C) 2024 Renesas Electronics Corporation.
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/units.h>
+#include <linux/watchdog.h>
+
+#define WDTRR 0x00 /* WDT Refresh Register RW, 8 */
+#define WDTCR 0x02 /* WDT Control Register RW, 16 */
+#define WDTSR 0x04 /* WDT Status Register RW, 16 */
+#define WDTRCR 0x06 /* WDT Reset Control Register RW, 8 */
+
+#define WDTCR_TOPS_1024 0x00
+#define WDTCR_TOPS_16384 0x03
+
+#define WDTCR_CKS_CLK_1 0x00
+#define WDTCR_CKS_CLK_256 0x50
+
+#define WDTCR_RPES_0 0x300
+#define WDTCR_RPES_75 0x000
+
+#define WDTCR_RPSS_25 0x00
+#define WDTCR_RPSS_100 0x3000
+
+#define WDTRCR_RSTIRQS BIT(7)
+
+#define MAX_TIMEOUT_CYCLES 16384
+#define CLOCK_DIV_BY_256 256
+
+#define WDT_DEFAULT_TIMEOUT 60U
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct rzv2h_wdt_priv {
+ void __iomem *base;
+ struct clk *pclk;
+ struct clk *oscclk;
+ struct reset_control *rstc;
+ struct watchdog_device wdev;
+};
+
+static int rzv2h_wdt_ping(struct watchdog_device *wdev)
+{
+ struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ /*
+ * The down-counter is refreshed and starts counting operation on
+ * a write of the values 00h and FFh to the WDTRR register.
+ */
+ writeb(0x0, priv->base + WDTRR);
+ writeb(0xFF, priv->base + WDTRR);
+
+ return 0;
+}
+
+static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
+{
+ struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ /* Configure the timeout, clock division ratio, and window start and end positions. */
+ writew(wdtcr, priv->base + WDTCR);
+
+ /* Enable interrupt output to the ICU. */
+ writeb(0, priv->base + WDTRCR);
+
+ /* Clear underflow flag and refresh error flag. */
+ writew(0, priv->base + WDTSR);
+}
+
+static int rzv2h_wdt_start(struct watchdog_device *wdev)
+{
+ struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ int ret;
+
+ ret = pm_runtime_resume_and_get(wdev->parent);
+ if (ret)
+ return ret;
+
+ ret = reset_control_deassert(priv->rstc);
+ if (ret) {
+ pm_runtime_put(wdev->parent);
+ return ret;
+ }
+
+ /* delay to handle clock halt after de-assert operation */
+ udelay(3);
+
+ /*
+ * WDTCR
+ * - CKS[7:4] - Clock Division Ratio Select - 0101b: oscclk/256
+ * - RPSS[13:12] - Window Start Position Select - 11b: 100%
+ * - RPES[9:8] - Window End Position Select - 11b: 0%
+ * - TOPS[1:0] - Timeout Period Select - 11b: 16384 cycles (3FFFh)
+ */
+ rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_256 | WDTCR_RPSS_100 |
+ WDTCR_RPES_0 | WDTCR_TOPS_16384);
+
+ /*
+ * Down counting starts after writing the sequence 00h -> FFh to the
+ * WDTRR register. Hence, call the ping operation after loading the counter.
+ */
+ rzv2h_wdt_ping(wdev);
+
+ return 0;
+}
+
+static int rzv2h_wdt_stop(struct watchdog_device *wdev)
+{
+ struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ int ret;
+
+ ret = reset_control_assert(priv->rstc);
+ if (ret)
+ return ret;
+
+ ret = pm_runtime_put(wdev->parent);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static const struct watchdog_info rzv2h_wdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+ .identity = "Renesas RZ/V2H WDT Watchdog",
+};
+
+static int rzv2h_wdt_restart(struct watchdog_device *wdev,
+ unsigned long action, void *data)
+{
+ struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ int ret;
+
+ if (!watchdog_active(wdev)) {
+ ret = clk_enable(priv->pclk);
+ if (ret)
+ return ret;
+
+ ret = clk_enable(priv->oscclk);
+ if (ret) {
+ clk_disable(priv->pclk);
+ return ret;
+ }
+
+ ret = reset_control_deassert(priv->rstc);
+ if (ret) {
+ clk_disable(priv->oscclk);
+ clk_disable(priv->pclk);
+ return ret;
+ }
+ } else {
+ /*
+ * Writing to the WDT Control Register (WDTCR) or WDT Reset
+ * Control Register (WDTRCR) is possible once between the
+ * release from the reset state and the first refresh operation.
+ * Therefore, issue a reset if the watchdog is active.
+ */
+ ret = reset_control_reset(priv->rstc);
+ if (ret)
+ return ret;
+ }
+
+ /* delay to handle clock halt after de-assert operation */
+ udelay(3);
+
+ /*
+ * WDTCR
+ * - CKS[7:4] - Clock Division Ratio Select - 0000b: oscclk/1
+ * - RPSS[13:12] - Window Start Position Select - 00b: 25%
+ * - RPES[9:8] - Window End Position Select - 00b: 75%
+ * - TOPS[1:0] - Timeout Period Select - 00b: 1024 cycles (03FFh)
+ */
+ rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_1 | WDTCR_RPSS_25 |
+ WDTCR_RPES_75 | WDTCR_TOPS_1024);
+
+ rzv2h_wdt_ping(wdev);
+
+ /* wait for underflow to trigger... */
+ udelay(5);
+
+ return 0;
+}
+
+static const struct watchdog_ops rzv2h_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = rzv2h_wdt_start,
+ .stop = rzv2h_wdt_stop,
+ .ping = rzv2h_wdt_ping,
+ .restart = rzv2h_wdt_restart,
+};
+
+static int rzv2h_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rzv2h_wdt_priv *priv;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ priv->pclk = devm_clk_get_prepared(&pdev->dev, "pclk");
+ if (IS_ERR(priv->pclk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk), "no pclk");
+
+ priv->oscclk = devm_clk_get_prepared(&pdev->dev, "oscclk");
+ if (IS_ERR(priv->oscclk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(priv->oscclk), "no oscclk");
+
+ priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+ if (IS_ERR(priv->rstc))
+ return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
+ "failed to get cpg reset");
+
+ priv->wdev.max_hw_heartbeat_ms = (MILLI * MAX_TIMEOUT_CYCLES * CLOCK_DIV_BY_256) /
+ clk_get_rate(priv->oscclk);
+ dev_dbg(dev, "max hw timeout of %dms\n", priv->wdev.max_hw_heartbeat_ms);
+
+ ret = devm_pm_runtime_enable(&pdev->dev);
+ if (ret)
+ return ret;
+
+ priv->wdev.min_timeout = 1;
+ priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
+ priv->wdev.info = &rzv2h_wdt_ident;
+ priv->wdev.ops = &rzv2h_wdt_ops;
+ priv->wdev.parent = dev;
+ watchdog_set_drvdata(&priv->wdev, priv);
+ watchdog_set_nowayout(&priv->wdev, nowayout);
+ watchdog_stop_on_unregister(&priv->wdev);
+
+ ret = watchdog_init_timeout(&priv->wdev, 0, dev);
+ if (ret)
+ dev_warn(dev, "Specified timeout invalid, using default");
+
+ return devm_watchdog_register_device(&pdev->dev, &priv->wdev);
+}
+
+static const struct of_device_id rzv2h_wdt_ids[] = {
+ { .compatible = "renesas,r9a09g057-wdt", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzv2h_wdt_ids);
+
+static struct platform_driver rzv2h_wdt_driver = {
+ .driver = {
+ .name = "rzv2h_wdt",
+ .of_match_table = rzv2h_wdt_ids,
+ },
+ .probe = rzv2h_wdt_probe,
+};
+module_platform_driver(rzv2h_wdt_driver);
+MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
+MODULE_DESCRIPTION("Renesas RZ/V2H(P) WDT Watchdog Driver");
projects / linux-block.git / commitdiff