Messages in this thread | | | Date | Tue, 26 May 2015 11:50:18 -0500 | From | Timur Tabi <> | Subject | Re: [PATCH v3 5/6] Watchdog: introduce ARM SBSA watchdog driver |
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On 05/25/2015 05:03 AM, fu.wei@linaro.org wrote:
> +/* > + * help functions for accessing 32bit registers of SBSA Generic Watchdog > + */ > +static void sbsa_gwdt_cf_write(unsigned int reg, u32 val, > + struct watchdog_device *wdd) > +{ > + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); > + > + writel_relaxed(val, gwdt->control_base + reg); > +} > + > +static void sbsa_gwdt_rf_write(unsigned int reg, u32 val, > + struct watchdog_device *wdd) > +{ > + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); > + > + writel_relaxed(val, gwdt->refresh_base + reg); > +} > + > +static u32 sbsa_gwdt_cf_read(unsigned int reg, struct watchdog_device *wdd) > +{ > + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); > + > + return readl_relaxed(gwdt->control_base + reg); > +}
I don't understand the value of these functions. You're just adding overhead to each read and write by dereferencing wdd every time. I would get rid of them and just call readl_relaxed() and writel_relaxed() directly.
> +/* > + * help functions for accessing 64bit WCV register > + */ > +static u64 sbsa_gwdt_get_wcv(struct watchdog_device *wdd) > +{ > + u32 wcv_lo, wcv_hi; > + > + do { > + wcv_hi = sbsa_gwdt_cf_read(SBSA_GWDT_WCV_HI, wdd); > + wcv_lo = sbsa_gwdt_cf_read(SBSA_GWDT_WCV_LO, wdd); > + } while (wcv_hi != sbsa_gwdt_cf_read(SBSA_GWDT_WCV_HI, wdd));
Please add a comment indicating that you're trying to read WCV atomically.
> + > + return (((u64)wcv_hi << 32) | wcv_lo); > +}
How about defining this macro:
#define make64(high, low) (((u64)(high) << 32) | (low))
and using it instead? That makes the code easier to read.
> + > +static void sbsa_gwdt_set_wcv(struct watchdog_device *wdd, u64 value) > +{ > + u32 wcv_lo, wcv_hi; > + > + wcv_lo = value & U32_MAX; > + wcv_hi = (value >> 32) & U32_MAX;
Use upper_32_bits() and lower_32_bits() instead.
> + > + sbsa_gwdt_cf_write(SBSA_GWDT_WCV_HI, wcv_hi, wdd); > + sbsa_gwdt_cf_write(SBSA_GWDT_WCV_LO, wcv_lo, wdd); > +} > + > +static void reload_timeout_to_wcv(struct watchdog_device *wdd)
This should be sbsa_gwdt_reload_timeout_to_wcv()
> +{ > + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); > + u64 wcv; > + > + wcv = arch_counter_get_cntvct() + > + (u64)(wdd->timeout - wdd->pretimeout) * gwdt->clk; > + > + sbsa_gwdt_set_wcv(wdd, wcv);
Shouldn't you program WCV and WOR together?
> +static int sbsa_gwdt_set_pretimeout(struct watchdog_device *wdd, > + unsigned int pretimeout) > +{ > + struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd); > + u32 wor; > + > + wdd->pretimeout = pretimeout; > + sbsa_gwdt_update_limits(wdd); > + > + if (!pretimeout) > + /* gives sbsa_gwdt_start a chance to setup timeout */ > + wor = gwdt->clk; > + else > + wor = pretimeout * gwdt->clk; > + > + /* refresh the WOR, that will cause an explicit watchdog refresh */ > + sbsa_gwdt_cf_write(SBSA_GWDT_WOR, wor, wdd);
Why not just ping the watchdog explicitely?
> +static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id) > +{ > + struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id; > + struct watchdog_device *wdd = &gwdt->wdd; > + u32 status; > + > + status = sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd); > + > + if (status & SBSA_GWDT_WCS_WS0)
This should always be true. Instead of reading WCS, I think you should just panic().
> +static int sbsa_gwdt_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct sbsa_gwdt *gwdt; > + struct watchdog_device *wdd; > + struct resource *res; > + void *rf_base, *cf_base; > + int irq; > + u32 clk, status; > + int ret = 0; > + u64 first_period_max = U64_MAX; > + > + /* > + * Get the frequency of system counter from > + * the cp15 interface of ARM Generic timer > + */ > + clk = arch_timer_get_cntfrq(); > + if (!clk) {
You have
depends on ARM_ARCH_TIMER
in your Kconfig, so you don't need to check the return of arch_timer_get_cntfrq(). It can never be zero.
Also, I would not use the variable name 'clk', because that's usually used for a "struct clk" object. I would call this "freq" instead.
-- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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