On 11/30/21 3:43 AM, Biju Das wrote:
Add Watchdog Timer driver for RZ/G2L SoC.
WDT IP block supports normal watchdog timer function and reset
request function due to CPU parity error.
This driver currently supports normal watchdog timer function
and later will add support for reset request function due to
CPU parity error.
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
V3->V4:
* Fixed the build issue reported by kernel test robot by Replacing the
macro WDT_CYCLE_MSEC with div64_ul for 64-bit division to fix 32-bit
kernels.
V2->V3:
* Added Rb tag from Guenter Roeck
V1->V2:
* started using clk_get/put instead of devm_clk_get/put
* Moved devm_add_action_or_reset after set_drvdata() and
* removed redundant action on devm_add_action_or_reset() failure.
RFC->V1
* Removed pclk_rate from priv.
* rzg2l_wdt_write() returns void and Removed tiemout related to register update
* rzg2l_wdt_init_timeout() returns void and removed delays.
* removed set_bit(WDOG_HW_RUNNING,..) as we can stop watchdog
* renamed reset_assert_clock_disable->reset_assert_pm_disable_put
* started using devm_reset_control_get_exclusive()
* removed platform_set_drvdata(pdev, priv) as there is no user
* removed watchdog_set_restart_priority(&priv->wdev, 0) as 0 is the default.
* removed remove callback as it is empty.
---
drivers/watchdog/Kconfig | 8 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/rzg2l_wdt.c | 260 +++++++++++++++++++++++++++++++++++
3 files changed, 269 insertions(+)
create mode 100644 drivers/watchdog/rzg2l_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9d222ba17ec6..4760ee981263 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -881,6 +881,14 @@ config RENESAS_RZAWDT
This driver adds watchdog support for the integrated watchdogs in the
Renesas RZ/A SoCs. These watchdogs can be used to reset a system.
+config RENESAS_RZG2LWDT
+ tristate "Renesas RZ/G2L WDT Watchdog"
+ depends on ARCH_RENESAS || COMPILE_TEST
+ select WATCHDOG_CORE
+ help
+ This driver adds watchdog support for the integrated watchdogs in the
+ Renesas RZ/G2L SoCs. These watchdogs can be used to reset a system.
+
config ASPEED_WATCHDOG
tristate "Aspeed BMC watchdog support"
depends on ARCH_ASPEED || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 2ee97064145b..9a3dc0bd271b 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
obj-$(CONFIG_RENESAS_RZAWDT) += rza_wdt.o
+obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
new file mode 100644
index 000000000000..69530b92fff9
--- /dev/null
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/G2L WDT Watchdog Driver
+ *
+ * Copyright (C) 2021 Renesas Electronics Corporation
+ */
+#include <linux/bitops.h>
+#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/watchdog.h>
+
+#define WDTCNT 0x00
+#define WDTSET 0x04
+#define WDTTIM 0x08
+#define WDTINT 0x0C
+#define WDTCNT_WDTEN BIT(0)
+#define WDTINT_INTDISP BIT(0)
+
+#define WDT_DEFAULT_TIMEOUT 60U
+
+/* Setting period time register only 12 bit set in WDTSET[31:20] */
+#define WDTSET_COUNTER_MASK (0xFFF00000)
+#define WDTSET_COUNTER_VAL(f) ((f) << 20)
+
+#define F2CYCLE_NSEC(f) (1000000000 / (f))
+
+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 rzg2l_wdt_priv {
+ void __iomem *base;
+ struct watchdog_device wdev;
+ struct reset_control *rstc;
+ unsigned long osc_clk_rate;
+ unsigned long delay;
+};
+
+static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
+{
+ /* delay timer when change the setting register */
+ ndelay(priv->delay);
+}
+
+static u32 rzg2l_wdt_get_cycle_msec(unsigned long cycle, u32 wdttime)
+{
+ u64 timer_cycle_ms = 1024 * 1024 * 1000000ULL * (wdttime + 1);
+
+ return div64_ul(timer_cycle_ms, cycle);
+}
A description might be warranted here. The return value appears to be a timeout
in seconds, based on
priv->wdev.max_timeout = rzg2l_wdt_get_cycle_msec(priv->osc_clk_rate, 0xfff);
but that is not what the function name suggests.
Also, the maximum timeouts seem to be excessive. Feeding the above function into test code,
I get
clk: 10000000 max timeout: 429496729
clk: 20000000 max timeout: 214748364
clk: 40000000 max timeout: 107374182
clk: 80000000 max timeout: 53687091
clk: 160000000 max timeout: 26843545
clk: 320000000 max timeout: 13421772
clk: 640000000 max timeout: 6710886
clk: 1280000000 max timeout: 3355443
That really doesn't look correct. Even in milli-seconds, a maximum
timeout of 429496729 ms or 429496.729 seconds at 10 MHz clock rate
seems high.
+
+static void rzg2l_wdt_write(struct rzg2l_wdt_priv *priv, u32 val, unsigned int reg)
+{
+ if (reg == WDTSET)
+ val &= WDTSET_COUNTER_MASK;
+
+ writel_relaxed(val, priv->base + reg);
+ /* Registers other than the WDTINT is always synchronized with WDT_CLK */
+ if (reg != WDTINT)
+ rzg2l_wdt_wait_delay(priv);
+}
+
+static void rzg2l_wdt_init_timeout(struct watchdog_device *wdev)
+{
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ u32 time_out;
+
+ /* Clear Lapsed Time Register and clear Interrupt */
+ rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
+ /* 2 consecutive overflow cycle needed to trigger reset */
+ time_out = (wdev->timeout / 2 * 1000000) / rzg2l_wdt_get_cycle_msec(priv->osc_clk_rate, 0);
This code effectively reduces timer granularity to 2 seconds. Is that on purpose ?
Why not something like
time_out = (wdev->timeout * (1000000 / 2)) / rzg2l_wdt_get_cycle_msec(priv->osc_clk_rate, 0);
instead ?
Also, feeding the maximum timeout as calculated by
rzg2l_wdt_get_cycle_msec(priv->osc_clk_rate, 0xfff)
into this expression yields really large numbers. Making things worse,
those long timeouts cause
wdev->timeout / 2 * 1000000
to overflow easily. This calculation alone suggests that the maximum timeout
value can not be larger than ~8589 to avoid that overflow.
More test code gives me:
clk: 10000000 max timeout: 429496729
timeout: 1s reg: 0x0
timeout: 2s reg: 0x9
timeout: 859s reg: 0xffb
Overflow: t=214748364 treg: 0x3d0916df
timeout: 214748364s reg: 0xffffffff
Overflow: t=429496729 treg: 0x7a122dbf
timeout: 429496729s reg: 0xffffffff
clk: 320000000 max timeout: 13421772
timeout: 1s reg: 0x0
timeout: 2s reg: 0x131
timeout: 27s reg: 0xf80
Overflow: t=6710886 treg: 0x3d0cd090
timeout: 6710886s reg: 0xffffffff
Overflow: t=13421772 treg: 0x7a19a120
timeout: 13421772s reg: 0xffffffff
and similar for other clock rates. This shows both the impact of the
artificial 2s granularity and the value overflows.
Something in the calculation of max_timeout or in the calculation
of the register value or both is wrong. Whatever it is, it needs
to get fixed.
Guenter
+ rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(time_out), WDTSET);
+}
+
+static int rzg2l_wdt_start(struct watchdog_device *wdev)
+{
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ reset_control_deassert(priv->rstc);
+ pm_runtime_get_sync(wdev->parent);
+
+ /* Initialize time out */
+ rzg2l_wdt_init_timeout(wdev);
+
+ /* Initialize watchdog counter register */
+ rzg2l_wdt_write(priv, 0, WDTTIM);
+
+ /* Enable watchdog timer*/
+ rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
+
+ return 0;
+}
+
+static int rzg2l_wdt_stop(struct watchdog_device *wdev)
+{
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ pm_runtime_put(wdev->parent);
+ reset_control_assert(priv->rstc);
+
+ return 0;
+}
+
+static int rzg2l_wdt_restart(struct watchdog_device *wdev,
+ unsigned long action, void *data)
+{
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ /* Reset the module before we modify any register */
+ reset_control_reset(priv->rstc);
+ pm_runtime_get_sync(wdev->parent);
+
+ /* smallest counter value to reboot soon */
+ rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(1), WDTSET);
+
+ /* Enable watchdog timer*/
+ rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
+
+ return 0;
+}
+
+static const struct watchdog_info rzg2l_wdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+ .identity = "Renesas RZ/G2L WDT Watchdog",
+};
+
+static int rzg2l_wdt_ping(struct watchdog_device *wdev)
+{
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
+
+ return 0;
+}
+
+static const struct watchdog_ops rzg2l_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = rzg2l_wdt_start,
+ .stop = rzg2l_wdt_stop,
+ .ping = rzg2l_wdt_ping,
+ .restart = rzg2l_wdt_restart,
+};
+
+static void rzg2l_wdt_reset_assert_pm_disable_put(void *data)
+{
+ struct watchdog_device *wdev = data;
+ struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ pm_runtime_put(wdev->parent);
+ pm_runtime_disable(wdev->parent);
+ reset_control_assert(priv->rstc);
+}
+
+static int rzg2l_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rzg2l_wdt_priv *priv;
+ unsigned long pclk_rate;
+ struct clk *wdt_clk;
+ 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);
+
+ /* Get watchdog main clock */
+ wdt_clk = clk_get(&pdev->dev, "oscclk");
+ if (IS_ERR(wdt_clk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no oscclk");
+
+ priv->osc_clk_rate = clk_get_rate(wdt_clk);
+ clk_put(wdt_clk);
+ if (!priv->osc_clk_rate)
+ return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
+
+ /* Get Peripheral clock */
+ wdt_clk = clk_get(&pdev->dev, "pclk");
+ if (IS_ERR(wdt_clk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no pclk");
+
+ pclk_rate = clk_get_rate(wdt_clk);
+ clk_put(wdt_clk);
+ if (!pclk_rate)
+ return dev_err_probe(&pdev->dev, -EINVAL, "pclk rate is 0");
+
+ priv->delay = F2CYCLE_NSEC(priv->osc_clk_rate) * 6 + F2CYCLE_NSEC(pclk_rate) * 9;
+
+ 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");
+
+ reset_control_deassert(priv->rstc);
+ pm_runtime_enable(&pdev->dev);
+ ret = pm_runtime_resume_and_get(&pdev->dev);
+ if (ret < 0) {
+ dev_err(dev, "pm_runtime_resume_and_get failed ret=%pe", ERR_PTR(ret));
+ goto out_pm_get;
+ }
+
+ priv->wdev.info = &rzg2l_wdt_ident;
+ priv->wdev.ops = &rzg2l_wdt_ops;
+ priv->wdev.parent = dev;
+ priv->wdev.min_timeout = 1;
+ priv->wdev.max_timeout = rzg2l_wdt_get_cycle_msec(priv->osc_clk_rate, 0xfff);
+ priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
+
+ watchdog_set_drvdata(&priv->wdev, priv);
+ ret = devm_add_action_or_reset(&pdev->dev,
+ rzg2l_wdt_reset_assert_pm_disable_put,
+ &priv->wdev);
+ if (ret < 0)
+ return ret;
+
+ 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);
+
+out_pm_get:
+ pm_runtime_disable(dev);
+ reset_control_assert(priv->rstc);
+
+ return ret;
+}
+
+static const struct of_device_id rzg2l_wdt_ids[] = {
+ { .compatible = "renesas,rzg2l-wdt", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
+
+static struct platform_driver rzg2l_wdt_driver = {
+ .driver = {
+ .name = "rzg2l_wdt",
+ .of_match_table = rzg2l_wdt_ids,
+ },
+ .probe = rzg2l_wdt_probe,
+};
+module_platform_driver(rzg2l_wdt_driver);
+
+MODULE_DESCRIPTION("Renesas RZ/G2L WDT Watchdog Driver");
+MODULE_AUTHOR("Biju Das <biju.das.jz@xxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
