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path: root/drivers/watchdog/rza_wdt.c
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Diffstat (limited to 'drivers/watchdog/rza_wdt.c')
-rw-r--r--drivers/watchdog/rza_wdt.c247
1 files changed, 247 insertions, 0 deletions
diff --git a/drivers/watchdog/rza_wdt.c b/drivers/watchdog/rza_wdt.c
new file mode 100644
index 000000000..fe6c2ed35
--- /dev/null
+++ b/drivers/watchdog/rza_wdt.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/A Series WDT Driver
+ *
+ * Copyright (C) 2017 Renesas Electronics America, Inc.
+ * Copyright (C) 2017 Chris Brandt
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define DEFAULT_TIMEOUT 30
+
+/* Watchdog Timer Registers */
+#define WTCSR 0
+#define WTCSR_MAGIC 0xA500
+#define WTSCR_WT BIT(6)
+#define WTSCR_TME BIT(5)
+#define WTSCR_CKS(i) (i)
+
+#define WTCNT 2
+#define WTCNT_MAGIC 0x5A00
+
+#define WRCSR 4
+#define WRCSR_MAGIC 0x5A00
+#define WRCSR_RSTE BIT(6)
+#define WRCSR_CLEAR_WOVF 0xA500 /* special value */
+
+/* The maximum CKS register setting value to get the longest timeout */
+#define CKS_3BIT 0x7
+#define CKS_4BIT 0xF
+
+#define DIVIDER_3BIT 16384 /* Clock divider when CKS = 0x7 */
+#define DIVIDER_4BIT 4194304 /* Clock divider when CKS = 0xF */
+
+struct rza_wdt {
+ struct watchdog_device wdev;
+ void __iomem *base;
+ struct clk *clk;
+ u8 count;
+ u8 cks;
+};
+
+static void rza_wdt_calc_timeout(struct rza_wdt *priv, int timeout)
+{
+ unsigned long rate = clk_get_rate(priv->clk);
+ unsigned int ticks;
+
+ if (priv->cks == CKS_4BIT) {
+ ticks = DIV_ROUND_UP(timeout * rate, DIVIDER_4BIT);
+
+ /*
+ * Since max_timeout was set in probe, we know that the timeout
+ * value passed will never calculate to a tick value greater
+ * than 256.
+ */
+ priv->count = 256 - ticks;
+
+ } else {
+ /* Start timer with longest timeout */
+ priv->count = 0;
+ }
+
+ pr_debug("%s: timeout set to %u (WTCNT=%d)\n", __func__,
+ timeout, priv->count);
+}
+
+static int rza_wdt_start(struct watchdog_device *wdev)
+{
+ struct rza_wdt *priv = watchdog_get_drvdata(wdev);
+
+ /* Stop timer */
+ writew(WTCSR_MAGIC | 0, priv->base + WTCSR);
+
+ /* Must dummy read WRCSR:WOVF at least once before clearing */
+ readb(priv->base + WRCSR);
+ writew(WRCSR_CLEAR_WOVF, priv->base + WRCSR);
+
+ rza_wdt_calc_timeout(priv, wdev->timeout);
+
+ writew(WRCSR_MAGIC | WRCSR_RSTE, priv->base + WRCSR);
+ writew(WTCNT_MAGIC | priv->count, priv->base + WTCNT);
+ writew(WTCSR_MAGIC | WTSCR_WT | WTSCR_TME |
+ WTSCR_CKS(priv->cks), priv->base + WTCSR);
+
+ return 0;
+}
+
+static int rza_wdt_stop(struct watchdog_device *wdev)
+{
+ struct rza_wdt *priv = watchdog_get_drvdata(wdev);
+
+ writew(WTCSR_MAGIC | 0, priv->base + WTCSR);
+
+ return 0;
+}
+
+static int rza_wdt_ping(struct watchdog_device *wdev)
+{
+ struct rza_wdt *priv = watchdog_get_drvdata(wdev);
+
+ writew(WTCNT_MAGIC | priv->count, priv->base + WTCNT);
+
+ pr_debug("%s: timeout = %u\n", __func__, wdev->timeout);
+
+ return 0;
+}
+
+static int rza_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
+{
+ wdev->timeout = timeout;
+ rza_wdt_start(wdev);
+ return 0;
+}
+
+static int rza_wdt_restart(struct watchdog_device *wdev, unsigned long action,
+ void *data)
+{
+ struct rza_wdt *priv = watchdog_get_drvdata(wdev);
+
+ /* Stop timer */
+ writew(WTCSR_MAGIC | 0, priv->base + WTCSR);
+
+ /* Must dummy read WRCSR:WOVF at least once before clearing */
+ readb(priv->base + WRCSR);
+ writew(WRCSR_CLEAR_WOVF, priv->base + WRCSR);
+
+ /*
+ * Start timer with fastest clock source and only 1 clock left before
+ * overflow with reset option enabled.
+ */
+ writew(WRCSR_MAGIC | WRCSR_RSTE, priv->base + WRCSR);
+ writew(WTCNT_MAGIC | 255, priv->base + WTCNT);
+ writew(WTCSR_MAGIC | WTSCR_WT | WTSCR_TME, priv->base + WTCSR);
+
+ /*
+ * Actually make sure the above sequence hits hardware before sleeping.
+ */
+ wmb();
+
+ /* Wait for WDT overflow (reset) */
+ udelay(20);
+
+ return 0;
+}
+
+static const struct watchdog_info rza_wdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+ .identity = "Renesas RZ/A WDT Watchdog",
+};
+
+static const struct watchdog_ops rza_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = rza_wdt_start,
+ .stop = rza_wdt_stop,
+ .ping = rza_wdt_ping,
+ .set_timeout = rza_set_timeout,
+ .restart = rza_wdt_restart,
+};
+
+static int rza_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rza_wdt *priv;
+ unsigned long rate;
+ 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->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk))
+ return PTR_ERR(priv->clk);
+
+ rate = clk_get_rate(priv->clk);
+ if (rate < 16384) {
+ dev_err(dev, "invalid clock rate (%ld)\n", rate);
+ return -ENOENT;
+ }
+
+ priv->wdev.info = &rza_wdt_ident;
+ priv->wdev.ops = &rza_wdt_ops;
+ priv->wdev.parent = dev;
+
+ priv->cks = (u8)(uintptr_t) of_device_get_match_data(dev);
+ if (priv->cks == CKS_4BIT) {
+ /* Assume slowest clock rate possible (CKS=0xF) */
+ priv->wdev.max_timeout = (DIVIDER_4BIT * U8_MAX) / rate;
+
+ } else if (priv->cks == CKS_3BIT) {
+ /* Assume slowest clock rate possible (CKS=7) */
+ rate /= DIVIDER_3BIT;
+
+ /*
+ * Since the max possible timeout of our 8-bit count
+ * register is less than a second, we must use
+ * max_hw_heartbeat_ms.
+ */
+ priv->wdev.max_hw_heartbeat_ms = (1000 * U8_MAX) / rate;
+ dev_dbg(dev, "max hw timeout of %dms\n",
+ priv->wdev.max_hw_heartbeat_ms);
+ }
+
+ priv->wdev.min_timeout = 1;
+ priv->wdev.timeout = DEFAULT_TIMEOUT;
+
+ watchdog_init_timeout(&priv->wdev, 0, dev);
+ watchdog_set_drvdata(&priv->wdev, priv);
+
+ ret = devm_watchdog_register_device(dev, &priv->wdev);
+ if (ret)
+ dev_err(dev, "Cannot register watchdog device\n");
+
+ return ret;
+}
+
+static const struct of_device_id rza_wdt_of_match[] = {
+ { .compatible = "renesas,r7s9210-wdt", .data = (void *)CKS_4BIT, },
+ { .compatible = "renesas,rza-wdt", .data = (void *)CKS_3BIT, },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rza_wdt_of_match);
+
+static struct platform_driver rza_wdt_driver = {
+ .probe = rza_wdt_probe,
+ .driver = {
+ .name = "rza_wdt",
+ .of_match_table = rza_wdt_of_match,
+ },
+};
+
+module_platform_driver(rza_wdt_driver);
+
+MODULE_DESCRIPTION("Renesas RZ/A WDT Driver");
+MODULE_AUTHOR("Chris Brandt <chris.brandt@renesas.com>");
+MODULE_LICENSE("GPL v2");