On 4/29/19 6:51 AM, Ludovic BARRE wrote:
Hi Guenter On 4/26/19 4:16 PM, Guenter Roeck wrote:On Fri, Apr 26, 2019 at 03:41:15PM +0200, Ludovic Barre wrote:From: Ludovic Barre <ludovic.barre@xxxxxx> This patch allows to define the max prescaler by compatible. To set a large range of timeout, the prescaler should be set dynamically (from the timeout request) to improve the resolution in order to have a timeout close to the expected value. Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx> --- drivers/watchdog/stm32_iwdg.c | 70 +++++++++++++++++++++++++------------------ 1 file changed, 41 insertions(+), 29 deletions(-) diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c index e00e3b3..91d0a89 100644 --- a/drivers/watchdog/stm32_iwdg.c +++ b/drivers/watchdog/stm32_iwdg.c @@ -34,18 +34,10 @@ #define KR_KEY_EWA 0x5555 /* write access enable */ #define KR_KEY_DWA 0x0000 /* write access disable */ -/* IWDG_PR register bit values */ -#define PR_4 0x00 /* prescaler set to 4 */ -#define PR_8 0x01 /* prescaler set to 8 */ -#define PR_16 0x02 /* prescaler set to 16 */ -#define PR_32 0x03 /* prescaler set to 32 */ -#define PR_64 0x04 /* prescaler set to 64 */ -#define PR_128 0x05 /* prescaler set to 128 */ -#define PR_256 0x06 /* prescaler set to 256 */ +#define PR_SHIFT 2 /* IWDG_RLR register values */ -#define RLR_MIN 0x07C /* min value supported by reload register */ -#define RLR_MAX 0xFFF /* max value supported by reload register */ +#define RLR_MAX GENMASK(11, 0) /* max value of reload register */ /* IWDG_SR register bit mask */ #define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ @@ -55,15 +47,28 @@ #define TIMEOUT_US 100000 #define SLEEP_US 1000 -#define HAS_PCLK true +struct stm32_iwdg_data { + bool has_pclk; + u32 max_prescaler; +}; + +static const struct stm32_iwdg_data stm32_iwdg_data = { + .has_pclk = false, + .max_prescaler = 256, +}; + +static const struct stm32_iwdg_data stm32mp1_iwdg_data = { + .has_pclk = true, + .max_prescaler = 1024, +}; struct stm32_iwdg { struct watchdog_device wdd; + const struct stm32_iwdg_data *data; void __iomem *regs; struct clk *clk_lsi; struct clk *clk_pclk; unsigned int rate; - bool has_pclk; }; static inline u32 reg_read(void __iomem *base, u32 reg) @@ -80,21 +85,30 @@ static int stm32_iwdg_start(struct watchdog_device *wdd) { struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); u32 val = FLAG_PVU | FLAG_RVU; - u32 reload; + u32 timeout, presc, iwdg_rlr, iwdg_pr; int ret; dev_dbg(wdd->parent, "%s\n", __func__); - /* prescaler fixed to 256 */ - reload = clamp_t(unsigned int, ((wdd->timeout * wdt->rate) / 256) - 1, - RLR_MIN, RLR_MAX); + timeout = clamp_t(unsigned int, wdd->timeout, + wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); + + if (timeout != wdd->timeout) + dev_warn(wdd->parent, "timeout skrinked to %d\n", timeout); +Valid values for timeout should be set in the set_timeout function, not here. As such, there is no need for this warning. More specifically, if the selected timeout is between min_timeout and max_hw_heartbeat_ms, and the hardware can not meet the exact requested value, the set_timeout function should adjust wdd->timeout value accordingly.Ok, so I will adjust the timeout (with prescaler and reload look-up) value in set_timeout function. thanksExample: The requested timeout is 55 seconds, but the hardware can only support either 32 or 64 seconds. The set_timeout function should then set wdd->timeout to either 32 or 64. Furthermore, this is a valid condition. For example, the timeout could be set for one hour (or day), and the maximum heartbeat could be one minute. In that situation, the watchdog core handles heartbeat/ping requests. Again, this does not warrant a warning. On top of all that, if the hardware can not set a minimum timeout of 1 second, min_timeout should not be set to 1 second. It should be set to the actual minimum supportable value if that value is larger than 1 second.+ presc = DIV_ROUND_UP(timeout * wdt->rate, RLR_MAX + 1); + + /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ + presc = roundup_pow_of_two(presc); + iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; + iwdg_rlr = ((timeout * wdt->rate) / presc) - 1; /* enable write access */ reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); /* set prescaler & reload registers */ - reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ - reg_write(wdt->regs, IWDG_RLR, reload); + reg_write(wdt->regs, IWDG_PR, iwdg_pr); + reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); /* wait for the registers to be updated (max 100ms) */ @@ -150,7 +164,7 @@ static int stm32_iwdg_clk_init(struct platform_device *pdev, } /* optional peripheral clock */ - if (wdt->has_pclk) { + if (wdt->data->has_pclk) { wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk"); if (IS_ERR(wdt->clk_pclk)) { dev_err(&pdev->dev, "Unable to get pclk clock\n"); @@ -191,8 +205,8 @@ static const struct watchdog_ops stm32_iwdg_ops = { }; static const struct of_device_id stm32_iwdg_of_match[] = { - { .compatible = "st,stm32-iwdg", .data = (void *)!HAS_PCLK }, - { .compatible = "st,stm32mp1-iwdg", .data = (void *)HAS_PCLK }, + { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, + { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, { /* end node */ } }; MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); @@ -200,20 +214,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); static int stm32_iwdg_probe(struct platform_device *pdev) { struct watchdog_device *wdd; - const struct of_device_id *match; struct stm32_iwdg *wdt; struct resource *res; int ret; - match = of_match_device(stm32_iwdg_of_match, &pdev->dev); - if (!match) - return -ENODEV; - wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); if (!wdt) return -ENOMEM; - wdt->has_pclk = match->data; + wdt->data = of_device_get_match_data(&pdev->dev); + if (!wdt->data) + return -ENODEV; /* This is the timer base. */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); @@ -231,8 +242,9 @@ static int stm32_iwdg_probe(struct platform_device *pdev) wdd = &wdt->wdd; wdd->info = &stm32_iwdg_info; wdd->ops = &stm32_iwdg_ops; - wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate; - wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate; + wdd->min_timeout = 1;Is this guaranteed to be no larger than 1 under all circumstances ? [ Not that the old code was necessarily correct - it might have set min_timeout to 0 if wdt->rate is high ]Infact, for not guaranteed the min timeout at 1s, the input clock (wdt->rate) should be < at 12Hz. On ST micro controller/processor the wdt->rate is based on LSI (Low Speed Internal) clock which is defined around 32KHz-39KHz I wanted avoid to set 0, due to min_timeout definition ("unsigned int" in struct watchdog_device) and comparator used in watchdog_timeout_invalid function. if the calculated value is < 1 => I could set 1, else I round on UP or Down value?
The minimum is 1 second. Other than that, if you want to round it up or down is really your call. The easiest would probably be to use DIV_ROUND_UP(); that would take care of all situations. Thanks, Guenter
Regards, Ludo+ wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * + 1000) / wdt->rate; wdd->parent = &pdev->dev; watchdog_set_drvdata(wdd, wdt); -- 2.7.4
