Re: [PATCH 1/4 v11] arm: use device tree to get smp_twd clock

Rafael J. Wysocki
2013-01-25T20:57:04Z

On Friday, January 25, 2013 01:46:42 PM Mark Langsdorf wrote:
> From: Rob Herring <rob.herring@calxeda.com>
>
> Move clk setup to twd_local_timer_common_register and rely on
> twd_timer_rate being 0 to force calibration if there is no clock.
> Remove common_setup_called as it is no longer needed.
>
> Signed-off-by: Rob Herring <rob.herring@calxeda.com>
> Signed-off-by: Mark Langsdorf <mark.langsdorf@calxeda.com>

Russell, is this fine with you?

Rafael

> ---
> Changes from v10
> Reworked to simplify the logic as suggested by Russell King.
> Changes from v9
> Updated to work with 3.8 kernel.
> Changes from v4, v5, v6, v7, v8
> None.
> Changes from v3
> No longer setting *clk to NULL in twd_get_clock().
> Changes from v2
> Turned the check for the node pointer into an if-then-else statement.
> Removed the second, redundant clk_get_rate.
> Changes from v1
> None.
>
> arch/arm/kernel/smp_twd.c | 53 +++++++++++++++++------------------------------
> 1 file changed, 19 insertions(+), 34 deletions(-)
>
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 49f335d..ae0c7bb 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -31,7 +31,6 @@ static void __iomem *twd_base;
>
> static struct clk *twd_clk;
> static unsigned long twd_timer_rate;
> -static bool common_setup_called;
> static DEFINE_PER_CPU(bool, percpu_setup_called);
>
> static struct clock_event_device __percpu **twd_evt;
> @@ -239,25 +238,28 @@ static irqreturn_t twd_handler(int irq, void *dev_id)
> return IRQ_NONE;
> }
>
> -static struct clk *twd_get_clock(void)
> +static void twd_get_clock(struct device_node *np)
> {
> - struct clk *clk;
> int err;
>
> - clk = clk_get_sys("smp_twd", NULL);
> - if (IS_ERR(clk)) {
> - pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
> - return clk;
> + if (np)
> + twd_clk = of_clk_get(np, 0);
> + else
> + twd_clk = clk_get_sys("smp_twd", NULL);
> +
> + if (IS_ERR(twd_clk)) {
> + pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
> + return;
> }
>
> - err = clk_prepare_enable(clk);
> + err = clk_prepare_enable(twd_clk);
> if (err) {
> pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
> - clk_put(clk);
> - return ERR_PTR(err);
> + clk_put(twd_clk);
> + return;
> }
>
> - return clk;
> + twd_timer_rate = clk_get_rate(twd_clk);
> }
>
> /*
> @@ -280,26 +282,7 @@ static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
> }
> per_cpu(percpu_setup_called, cpu) = true;
>
> - /*
> - * This stuff only need to be done once for the entire TWD cluster
> - * during the runtime of the system.
> - */
> - if (!common_setup_called) {
> - twd_clk = twd_get_clock();
> -
> - /*
> - * We use IS_ERR_OR_NULL() here, because if the clock stubs
> - * are active we will get a valid clk reference which is
> - * however NULL and will return the rate 0. In that case we
> - * need to calibrate the rate instead.
> - */
> - if (!IS_ERR_OR_NULL(twd_clk))
> - twd_timer_rate = clk_get_rate(twd_clk);
> - else
> - twd_calibrate_rate();
> -
> - common_setup_called = true;
> - }
> + twd_calibrate_rate();
>
> /*
> * The following is done once per CPU the first time .setup() is
> @@ -330,7 +313,7 @@ static struct local_timer_ops twd_lt_ops __cpuinitdata = {
> .stop = twd_timer_stop,
> };
>
> -static int __init twd_local_timer_common_register(void)
> +static int __init twd_local_timer_common_register(struct device_node *np)
> {
> int err;
>
> @@ -350,6 +333,8 @@ static int __init twd_local_timer_common_register(void)
> if (err)
> goto out_irq;
>
> + twd_get_clock(np);
> +
> return 0;
>
> out_irq:
> @@ -373,7 +358,7 @@ int __init twd_local_timer_register(struct twd_local_timer *tlt)
> if (!twd_base)
> return -ENOMEM;
>
> - return twd_local_timer_common_register();
> + return twd_local_timer_common_register(NULL);
> }
>
> #ifdef CONFIG_OF
> @@ -405,7 +390,7 @@ void __init twd_local_timer_of_register(void)
> goto out;
> }
>
> - err = twd_local_timer_common_register();
> + err = twd_local_timer_common_register(np);
>
> out:
> WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.