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Date: Fri, 10 Aug 2018 06:36:48 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Paul Cercueil <paul@...pouillou.net>
Cc: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Thierry Reding <thierry.reding@...il.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>,
James Hogan <jhogan@...nel.org>,
Jonathan Corbet <corbet@....net>,
Lee Jones <lee.jones@...aro.org>,
Mathieu Malaterre <malat@...ian.org>,
Ezequiel Garcia <ezequiel@...labora.co.uk>,
linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
linux-mips@...ux-mips.org, linux-doc@...r.kernel.org,
linux-clk@...r.kernel.org
Subject: Re: [PATCH v6 08/24] watchdog: jz4740: Use WDT clock provided by TCU
driver
On Thu, Aug 09, 2018 at 11:43:58PM +0200, Paul Cercueil wrote:
> Instead of requesting the "ext" clock and handling the watchdog clock
> divider and gating in the watchdog driver, we now request and use the
> "wdt" clock that is supplied by the ingenic-timer "TCU" driver.
>
> The major benefit is that the watchdog's clock rate and parent can now
> be specified from within devicetree, instead of hardcoded in the driver.
>
> Also, this driver won't poke anymore into the TCU registers to
> enable/disable the clock, as this is now handled by the TCU driver.
>
> On the bad side, we break the ABI with devicetree - as we now request a
> different clock. In this very specific case it is still okay, as every
> Ingenic JZ47xx-based board out there compile the devicetree within the
> kernel; so it's still time to push breaking changes, in order to get a
> clean devicetree that won't break once it musn't.
>
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> drivers/watchdog/Kconfig | 2 +
> drivers/watchdog/jz4740_wdt.c | 86 +++++++++++++++++--------------------------
> 2 files changed, 36 insertions(+), 52 deletions(-)
>
> v5: New patch
>
> v6: - Split regmap change to new patch 09/24
> - The code now sets the WDT clock to the smallest rate possible and
> calculates the maximum timeout from that
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 9af07fd92763..834222abbbdb 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1476,7 +1476,9 @@ config INDYDOG
> config JZ4740_WDT
> tristate "Ingenic jz4740 SoC hardware watchdog"
> depends on MACH_JZ4740 || MACH_JZ4780
> + depends on COMMON_CLK
> select WATCHDOG_CORE
> + select INGENIC_TIMER
> help
> Hardware driver for the built-in watchdog timer on Ingenic jz4740 SoCs.
>
> diff --git a/drivers/watchdog/jz4740_wdt.c b/drivers/watchdog/jz4740_wdt.c
> index ec4d99a830ba..1d504ecf45e1 100644
> --- a/drivers/watchdog/jz4740_wdt.c
> +++ b/drivers/watchdog/jz4740_wdt.c
> @@ -26,25 +26,9 @@
> #include <linux/err.h>
> #include <linux/of.h>
>
> -#include <asm/mach-jz4740/timer.h>
> -
> #define JZ_REG_WDT_TIMER_DATA 0x0
> #define JZ_REG_WDT_COUNTER_ENABLE 0x4
> #define JZ_REG_WDT_TIMER_COUNTER 0x8
> -#define JZ_REG_WDT_TIMER_CONTROL 0xC
> -
> -#define JZ_WDT_CLOCK_PCLK 0x1
> -#define JZ_WDT_CLOCK_RTC 0x2
> -#define JZ_WDT_CLOCK_EXT 0x4
> -
> -#define JZ_WDT_CLOCK_DIV_SHIFT 3
> -
> -#define JZ_WDT_CLOCK_DIV_1 (0 << JZ_WDT_CLOCK_DIV_SHIFT)
> -#define JZ_WDT_CLOCK_DIV_4 (1 << JZ_WDT_CLOCK_DIV_SHIFT)
> -#define JZ_WDT_CLOCK_DIV_16 (2 << JZ_WDT_CLOCK_DIV_SHIFT)
> -#define JZ_WDT_CLOCK_DIV_64 (3 << JZ_WDT_CLOCK_DIV_SHIFT)
> -#define JZ_WDT_CLOCK_DIV_256 (4 << JZ_WDT_CLOCK_DIV_SHIFT)
> -#define JZ_WDT_CLOCK_DIV_1024 (5 << JZ_WDT_CLOCK_DIV_SHIFT)
>
> #define DEFAULT_HEARTBEAT 5
> #define MAX_HEARTBEAT 2048
> @@ -65,7 +49,8 @@ MODULE_PARM_DESC(heartbeat,
> struct jz4740_wdt_drvdata {
> struct watchdog_device wdt;
> void __iomem *base;
> - struct clk *rtc_clk;
> + struct clk *clk;
> + unsigned long clk_rate;
> };
>
> static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)
> @@ -80,31 +65,12 @@ static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
> unsigned int new_timeout)
> {
> struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> - unsigned int rtc_clk_rate;
> - unsigned int timeout_value;
> - unsigned short clock_div = JZ_WDT_CLOCK_DIV_1;
> -
> - rtc_clk_rate = clk_get_rate(drvdata->rtc_clk);
> -
> - timeout_value = rtc_clk_rate * new_timeout;
> - while (timeout_value > 0xffff) {
> - if (clock_div == JZ_WDT_CLOCK_DIV_1024) {
> - /* Requested timeout too high;
> - * use highest possible value. */
> - timeout_value = 0xffff;
> - break;
> - }
> - timeout_value >>= 2;
> - clock_div += (1 << JZ_WDT_CLOCK_DIV_SHIFT);
> - }
> + u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);
>
> writeb(0x0, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
> - writew(clock_div, drvdata->base + JZ_REG_WDT_TIMER_CONTROL);
>
> writew((u16)timeout_value, drvdata->base + JZ_REG_WDT_TIMER_DATA);
> writew(0x0, drvdata->base + JZ_REG_WDT_TIMER_COUNTER);
> - writew(clock_div | JZ_WDT_CLOCK_RTC,
> - drvdata->base + JZ_REG_WDT_TIMER_CONTROL);
>
> writeb(0x1, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
>
> @@ -114,7 +80,13 @@ static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
>
> static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
> {
> - jz4740_timer_enable_watchdog();
> + struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
> + int ret;
> +
> + ret = clk_prepare_enable(drvdata->clk);
> + if (ret)
> + return ret;
> +
> jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>
> return 0;
> @@ -125,7 +97,7 @@ static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
> struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
>
> writeb(0x0, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
> - jz4740_timer_disable_watchdog();
> + clk_disable_unprepare(drvdata->clk);
>
> return 0;
> }
> @@ -163,26 +135,42 @@ MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
>
> static int jz4740_wdt_probe(struct platform_device *pdev)
> {
> + struct device *dev = &pdev->dev;
> struct jz4740_wdt_drvdata *drvdata;
> struct watchdog_device *jz4740_wdt;
> struct resource *res;
> + long rate;
> int ret;
>
> - drvdata = devm_kzalloc(&pdev->dev, sizeof(struct jz4740_wdt_drvdata),
> - GFP_KERNEL);
> + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> if (!drvdata)
> return -ENOMEM;
>
> - if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
> - heartbeat = DEFAULT_HEARTBEAT;
> + drvdata->clk = devm_clk_get(&pdev->dev, "wdt");
> + if (IS_ERR(drvdata->clk)) {
> + dev_err(&pdev->dev, "cannot find WDT clock\n");
> + return PTR_ERR(drvdata->clk);
> + }
> +
> + /* Set smallest clock possible */
> + rate = clk_round_rate(drvdata->clk, 1);
> + if (rate < 0)
> + return rate;
>
> + ret = clk_set_rate(drvdata->clk, rate);
> + if (ret)
> + return ret;
> +
> + drvdata->clk_rate = rate;
> jz4740_wdt = &drvdata->wdt;
> jz4740_wdt->info = &jz4740_wdt_info;
> jz4740_wdt->ops = &jz4740_wdt_ops;
> - jz4740_wdt->timeout = heartbeat;
> jz4740_wdt->min_timeout = 1;
> - jz4740_wdt->max_timeout = MAX_HEARTBEAT;
> - jz4740_wdt->parent = &pdev->dev;
> + jz4740_wdt->max_timeout = 0xffff / rate;
> + jz4740_wdt->timeout = clamp(heartbeat,
> + jz4740_wdt->min_timeout,
> + jz4740_wdt->max_timeout);
> + jz4740_wdt->parent = dev;
> watchdog_set_nowayout(jz4740_wdt, nowayout);
> watchdog_set_drvdata(jz4740_wdt, drvdata);
>
> @@ -191,12 +179,6 @@ static int jz4740_wdt_probe(struct platform_device *pdev)
> if (IS_ERR(drvdata->base))
> return PTR_ERR(drvdata->base);
>
> - drvdata->rtc_clk = devm_clk_get(&pdev->dev, "rtc");
> - if (IS_ERR(drvdata->rtc_clk)) {
> - dev_err(&pdev->dev, "cannot find RTC clock\n");
> - return PTR_ERR(drvdata->rtc_clk);
> - }
> -
> ret = devm_watchdog_register_device(&pdev->dev, &drvdata->wdt);
> if (ret < 0)
> return ret;
> --
> 2.11.0
>
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