Re: [PATCH 1/3] cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs

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On Fri, Jan 18, 2013 at 7:50 PM, Andrew Lunn <andrew@xxxxxxx> wrote:
> The Marvell Kirkwood SoCs have simple cpufreq support in hardware. The
> CPU can either use the a high speed cpu clock, or the slower DDR
> clock. Add a driver to swap between these two clock sources.
>
> Signed-off-by: Andrew Lunn <andrew@xxxxxxx>
> ---
>  drivers/clk/mvebu/clk-gating-ctrl.c |    1 +
>  drivers/cpufreq/Kconfig.arm         |    6 +
>  drivers/cpufreq/Makefile            |    1 +
>  drivers/cpufreq/kirkwood-cpufreq.c  |  273 +++++++++++++++++++++++++++++++++++
>  4 files changed, 281 insertions(+)
>  create mode 100644 drivers/cpufreq/kirkwood-cpufreq.c
>
> diff --git a/drivers/clk/mvebu/clk-gating-ctrl.c b/drivers/clk/mvebu/clk-gating-ctrl.c
> index 8fa5408..ebf141d 100644
> --- a/drivers/clk/mvebu/clk-gating-ctrl.c
> +++ b/drivers/clk/mvebu/clk-gating-ctrl.c
> @@ -193,6 +193,7 @@ static const struct mvebu_soc_descr __initconst kirkwood_gating_descr[] = {
>         { "runit", NULL, 7 },
>         { "xor0", NULL, 8 },
>         { "audio", NULL, 9 },
> +       { "powersave", "cpuclk", 11 },
>         { "sata0", NULL, 14 },
>         { "sata1", NULL, 15 },
>         { "xor1", NULL, 16 },
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index a0b3661..08ca366 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -77,6 +77,12 @@ config ARM_EXYNOS5250_CPUFREQ
>           This adds the CPUFreq driver for Samsung EXYNOS5250
>           SoC.
>
> +config ARM_KIRKWOOD_CPUFREQ
> +        def_bool ARCH_KIRKWOOD && OF
> +       help
> +         This adds the CPUFreq driver for Marvell Kirkwood
> +         SoCs.
> +
>  config ARM_SPEAR_CPUFREQ
>         bool "SPEAr CPUFreq support"
>         depends on PLAT_SPEAR
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index fadc4d4..39a0ffe 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -50,6 +50,7 @@ obj-$(CONFIG_ARM_EXYNOS_CPUFREQ)      += exynos-cpufreq.o
>  obj-$(CONFIG_ARM_EXYNOS4210_CPUFREQ)   += exynos4210-cpufreq.o
>  obj-$(CONFIG_ARM_EXYNOS4X12_CPUFREQ)   += exynos4x12-cpufreq.o
>  obj-$(CONFIG_ARM_EXYNOS5250_CPUFREQ)   += exynos5250-cpufreq.o
> +obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ)     += kirkwood-cpufreq.o
>  obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)     += omap-cpufreq.o
>  obj-$(CONFIG_ARM_SPEAR_CPUFREQ)                += spear-cpufreq.o
>
> diff --git a/drivers/cpufreq/kirkwood-cpufreq.c b/drivers/cpufreq/kirkwood-cpufreq.c
> new file mode 100644
> index 0000000..4f0a435
> --- /dev/null
> +++ b/drivers/cpufreq/kirkwood-cpufreq.c
> @@ -0,0 +1,273 @@
> +/*
> + *     kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
> + *
> + *     Copyright (C) 2013 Andrew Lunn <andrew@xxxxxxx>
> + *
> + *     This program is free software; you can redistribute it and/or
> + *     modify it under the terms of the GNU General Public License
> + *     as published by the Free Software Foundation; either version
> + *     2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/clk-provider.h>

why do you need this one?

> +#include <linux/of.h>
> +#include <linux/delay.h>
> +#include <linux/clk.h>
> +#include <linux/cpufreq.h>
> +#include <linux/timex.h>
> +#include <linux/io.h>
> +#include <asm/proc-fns.h>

would be better to keep them in alphabetical order to guarantee that we don't
include anything twice.

> +#define CPU_SW_INT_BLK BIT(28)
> +
> +
> +#include <linux/clk-private.h>
> +
> +static struct priv
> +{
> +       struct clk *cpu_clk;
> +       struct clk *ddr_clk;
> +       struct clk *powersave_clk;
> +       struct device *dev;
> +       void __iomem *base;
> +} priv;
> +
> +#define STATE_CPU_FREQ 0x01
> +#define STATE_DDR_FREQ 0x02
> +
> +/* Kirkwood can swap the clock to the CPU between two clocks:
> + *
> + * - cpu clk
> + * - ddr clk
> + *
> + * The frequencies are set at runtime before registering this *
> + * table. */

wrong multiline comment style.

/*
 * ....
 * ....
 */

> +static struct cpufreq_frequency_table kirkwood_freq_table[] = {
> +       {STATE_CPU_FREQ,        0}, /* CPU uses cpuclk */
> +       {STATE_DDR_FREQ,        0}, /* CPU uses ddrclk */
> +       {0,                     CPUFREQ_TABLE_END},
> +};

I don't know if anything is broken now, but i would like to keep index
in freq_table.index
field as the actual index in the table.

i.e, currently you have order as 1,2,0 .. but should have been 0, 1, 2

> +static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
> +{
> +       if (__clk_is_enabled(priv.powersave_clk))
> +               return kirkwood_freq_table[1].frequency;
> +       return kirkwood_freq_table[0].frequency;
> +}
> +
> +static void kirkwood_cpufreq_set_cpu_state(unsigned int index)
> +{
> +
> +       struct cpufreq_freqs freqs;
> +       unsigned int state = kirkwood_freq_table[index].index;
> +       unsigned long reg;
> +
> +       freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
> +       freqs.new = kirkwood_freq_table[index].frequency;
> +       freqs.cpu = 0; /* Kirkwood is UP */
> +
> +       cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
> +
> +       dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
> +               kirkwood_freq_table[index].frequency);
> +       dev_dbg(priv.dev, "old frequency was %i KHz\n",
> +               kirkwood_cpufreq_get_cpu_frequency(0));
> +
> +       if (freqs.old != freqs.new) {
> +               local_irq_disable();
> +
> +               /* Disable interrupts to the CPU */
> +               reg = readl_relaxed(priv.base);
> +               reg |= CPU_SW_INT_BLK;
> +               writel(reg, priv.base);
> +
> +               switch (state) {
> +               case STATE_CPU_FREQ:
> +                       clk_disable(priv.powersave_clk);
> +                       break;
> +               case STATE_DDR_FREQ:
> +                       clk_enable(priv.powersave_clk);
> +                       break;
> +               default:
> +                       dev_err(priv.dev, "Unexpected cpufreq state");
> +               }
> +
> +               /* Wait-for-Interrupt, which the hardware changes frequency */
> +               cpu_do_idle();
> +
> +               /* Enable interrupts to the CPU */
> +               reg = readl_relaxed(priv.base);
> +               reg &= ~CPU_SW_INT_BLK;
> +               writel(reg, priv.base);
> +
> +               local_irq_enable();
> +       }
> +       cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
> +};
> +
> +static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
> +{
> +       return cpufreq_frequency_table_verify(policy, &kirkwood_freq_table[0]);
> +}
> +
> +static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
> +                           unsigned int target_freq,
> +                           unsigned int relation)
> +{
> +       unsigned int index = 0;
> +
> +       if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
> +                               target_freq, relation, &index))
> +               return -EINVAL;
> +
> +       kirkwood_cpufreq_set_cpu_state(index);

You can get this function inlined here.. as it is only called from
this location.

> +       return 0;
> +}
> +
> +/*
> + *     Module init and exit code
> + */
> +static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
> +{
> +       int result;
> +
> +       /* cpuinfo and default policy values */
> +       policy->cpuinfo.transition_latency = 5000; /* 5uS */
> +       policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
> +
> +       result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
> +       if (result)
> +               return result;
> +
> +       cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
> +
> +       return 0;
> +}
> +
> +static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
> +{
> +       cpufreq_frequency_table_put_attr(policy->cpu);
> +       return 0;
> +}
> +
> +static struct freq_attr *kirkwood_cpufreq_attr[] = {
> +       &cpufreq_freq_attr_scaling_available_freqs,
> +       NULL,
> +};
> +
> +
> +static struct cpufreq_driver kirkwood_cpufreq_driver = {
> +       .get    = kirkwood_cpufreq_get_cpu_frequency,
> +       .verify = kirkwood_cpufreq_verify,
> +       .target = kirkwood_cpufreq_target,
> +       .init   = kirkwood_cpufreq_cpu_init,
> +       .exit   = kirkwood_cpufreq_cpu_exit,
> +       .name   = "kirkwood_freq",
> +       .owner  = THIS_MODULE,
> +       .attr   = kirkwood_cpufreq_attr,
> +};
> +
> +static int kirkwood_cpufreq_probe(struct platform_device *pdev)
> +{
> +       struct device_node *np = of_find_compatible_node(
> +               NULL, NULL, "marvell,kirkwood-core-clock");

Is cpu0 a better location for adding this entry?

> +       struct of_phandle_args clkspec;
> +       struct resource *res;
> +       int err;
> +
> +       priv.dev = &pdev->dev;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "Cannot get memory resource\n");
> +               return -ENODEV;
> +       }
> +       priv.base = devm_request_and_ioremap(&pdev->dev, res);
> +       if (!priv.base) {
> +               dev_err(&pdev->dev, "Cannot ioremap\n");
> +               return -ENOMEM;
> +       }
> +
> +       clkspec.np = np;
> +       clkspec.args_count = 1;
> +       clkspec.args[0] = 1;
> +
> +       priv.cpu_clk = of_clk_get_from_provider(&clkspec);
> +       if (IS_ERR(priv.cpu_clk)) {
> +               dev_err(priv.dev, "Unable to get cpuclk");
> +               return PTR_ERR(priv.cpu_clk);
> +       }
> +
> +       clk_prepare_enable(priv.cpu_clk);
> +       kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
> +
> +       clkspec.args[0] = 3;
> +       priv.ddr_clk = of_clk_get_from_provider(&clkspec);
> +       if (IS_ERR(priv.ddr_clk)) {
> +               dev_err(priv.dev, "Unable to get ddrclk");
> +               err = PTR_ERR(priv.ddr_clk);
> +               goto out_cpu;
> +       }
> +
> +       clk_prepare_enable(priv.ddr_clk);
> +       kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
> +
> +       np = of_find_compatible_node(NULL, NULL,
> +                                    "marvell,kirkwood-gating-clock");
> +       clkspec.np = np;
> +       clkspec.args[0] = 11;
> +       priv.powersave_clk = of_clk_get_from_provider(&clkspec);
> +       if (IS_ERR(priv.powersave_clk)) {
> +               dev_err(priv.dev, "Unable to get powersave");
> +               err = PTR_ERR(priv.powersave_clk);
> +               goto out_ddr;
> +       }
> +       clk_prepare(priv.powersave_clk);

want to check return value?

> +       err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
> +       if (!err)
> +               return 0;
> +       dev_err(priv.dev, "Failed to register cpufreq driver");
> +
> +       clk_disable_unprepare(priv.powersave_clk);
> +out_ddr:
> +       clk_disable_unprepare(priv.ddr_clk);
> +out_cpu:
> +       clk_disable_unprepare(priv.cpu_clk);
> +
> +       return err;
> +}
> +
> +
> +static int kirkwood_cpufreq_remove(struct platform_device *pdev)
> +{
> +       cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
> +
> +       clk_disable_unprepare(priv.powersave_clk);
> +       clk_disable_unprepare(priv.ddr_clk);
> +       clk_disable_unprepare(priv.cpu_clk);
> +
> +       return 0;
> +}
> +
> +static struct platform_driver kirkwood_cpufreq_platform_driver = {
> +       .probe = kirkwood_cpufreq_probe,
> +       .remove = kirkwood_cpufreq_remove,
> +       .driver = {
> +               .name = "kirkwood-cpufreq",
> +               .owner = THIS_MODULE,
> +       },
> +};
> +
> +module_platform_driver(kirkwood_cpufreq_platform_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Andrew Lunn <andrew@xxxxxxx");
> +MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
> +MODULE_ALIAS("platform:kirkwood-cpufreq");
> --
> 1.7.10.4
>
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