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Date:	Fri, 17 Oct 2014 13:38:54 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Tang Yuantian-B29983 <B29983@...escale.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linuxppc-dev@...abs.org" <linuxppc-dev@...abs.org>,
	Tang Yuantian <Yuantian.Tang@...escale.com>
Subject: Re: [PATCH] cpufreq: qoriq: Make the driver usable on all QorIQ platforms

On 17 October 2014 08:43,  <B29983@...escale.com> wrote:

Hi B29983 :)

> From: Tang Yuantian <Yuantian.Tang@...escale.com>
>
> Freescale introduced new ARM core-based SoCs which support dynamic
> frequency switch feature. DFS on new SoCs are compatible with current
> PowerPC CoreNet platforms. In order to support those new platforms,
> this driver needs to be slightly adjusted. The main changes include:
>
> 1. Changed the names of driver and functions in driver.
> 2. Added two new functions get_cpu_physical_id() and get_bus_freq().
> 3. Used a new way to get all the CPUs which sharing clock wire.
>
> Signed-off-by: Tang Yuantian <Yuantian.Tang@...escale.com>
> ---
>  drivers/cpufreq/Kconfig.arm                        |   8 ++
>  drivers/cpufreq/Kconfig.powerpc                    |  11 +-
>  drivers/cpufreq/Makefile                           |   2 +-
>  .../{ppc-corenet-cpufreq.c => qoriq-cpufreq.c}     | 150 ++++++++++++++-------
>  4 files changed, 114 insertions(+), 57 deletions(-)
>  rename drivers/cpufreq/{ppc-corenet-cpufreq.c => qoriq-cpufreq.c} (72%)
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 83a75dc..1925ae94 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -247,3 +247,11 @@ config ARM_TEGRA_CPUFREQ
>         default y
>         help
>           This adds the CPUFreq driver support for TEGRA SOCs.
> +
> +config QORIQ_CPUFREQ
> +       tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
> +       depends on OF && COMMON_CLK
> +       select CLK_PPC_CORENET
> +       help
> +         This adds the CPUFreq driver support for Freescale QorIQ SoCs
> +         which are capable of changing the CPU's frequency dynamically.
> diff --git a/drivers/cpufreq/Kconfig.powerpc b/drivers/cpufreq/Kconfig.powerpc
> index 72564b7..3a34248 100644
> --- a/drivers/cpufreq/Kconfig.powerpc
> +++ b/drivers/cpufreq/Kconfig.powerpc
> @@ -23,14 +23,13 @@ config CPU_FREQ_MAPLE
>           This adds support for frequency switching on Maple 970FX
>           Evaluation Board and compatible boards (IBM JS2x blades).
>
> -config PPC_CORENET_CPUFREQ
> -       tristate "CPU frequency scaling driver for Freescale E500MC SoCs"
> -       depends on PPC_E500MC && OF && COMMON_CLK
> +config QORIQ_CPUFREQ
> +       tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
> +       depends on OF && COMMON_CLK
>         select CLK_PPC_CORENET
>         help
> -         This adds the CPUFreq driver support for Freescale e500mc,
> -         e5500 and e6500 series SoCs which are capable of changing
> -         the CPU's frequency dynamically.
> +         This adds the CPUFreq driver support for Freescale QorIQ SoCs
> +         which are capable of changing the CPU's frequency dynamically.
>
>  config CPU_FREQ_PMAC
>         bool "Support for Apple PowerBooks"

Don't need this duplication at all. Just move this to Kconfig instead
of .arm and ppc.

> diff --git a/drivers/cpufreq/ppc-corenet-cpufreq.c b/drivers/cpufreq/qoriq-cpufreq.c

>  /**
>   * struct cpu_data - per CPU data struct
> @@ -69,9 +68,6 @@ static const u32 *fmask;
>
>  static DEFINE_PER_CPU(struct cpu_data *, cpu_data);
>
> -/* cpumask in a cluster */
> -static DEFINE_PER_CPU(cpumask_var_t, cpu_mask);
> -
>  #ifndef CONFIG_SMP
>  static inline const struct cpumask *cpu_core_mask(int cpu)
>  {
> @@ -79,6 +75,79 @@ static inline const struct cpumask *cpu_core_mask(int cpu)
>  }
>  #endif
>
> +#if defined(CONFIG_PPC_E500MC)
> +static int get_cpu_physical_id(int cpu)
> +{
> +       return get_hard_smp_processor_id(cpu);
> +}
> +#elif defined(CONFIG_ARM)

Wouldn't a #else work here as there are just two platforms we are
talking about ?

> +static int get_cpu_physical_id(int cpu)
> +{
> +       return topology_core_id(cpu);
> +}
> +#endif
> +
> +static u32 get_bus_freq(void)
> +{
> +       struct device_node *soc;
> +       u32 sysfreq;
> +
> +       soc = of_find_node_by_type(NULL, "soc");
> +       if (!soc)
> +               return 0;
> +
> +       if (of_property_read_u32(soc, "bus-frequency", &sysfreq))
> +               sysfreq = 0;
> +
> +       of_node_put(soc);
> +
> +       return sysfreq;
> +}
> +
> +static struct device_node *cpu_to_clk_node(int cpu)
> +{
> +       struct device_node *np, *clk_np;
> +
> +       if (!cpu_present(cpu))
> +               return NULL;
> +
> +       np = of_get_cpu_node(cpu, NULL);
> +       if (!np)
> +               return NULL;
> +
> +       clk_np = of_parse_phandle(np, "clocks", 0);
> +       if (!clk_np)
> +               return NULL;
> +
> +       of_node_put(np);
> +
> +       return clk_np;
> +}
> +
> +/* traverse cpu nodes to get cpu mask of sharing clock wire */
> +static void set_affected_cpus(struct cpufreq_policy *policy)
> +{
> +       struct device_node *np, *clk_np;
> +       struct cpumask *dstp = policy->cpus;
> +       int i;
> +
> +       np = cpu_to_clk_node(policy->cpu);
> +       if (!np)
> +               return;
> +
> +       for_each_present_cpu(i) {
> +               clk_np = cpu_to_clk_node(i);
> +               if (!clk_np)
> +                       continue;
> +
> +               if (clk_np == np)
> +                       cpumask_set_cpu(i, dstp);

So you are depending on matching the clock-nodes from DT for
getting this information, right ? There is nothing that the architecture
gives?

> +
> +               of_node_put(clk_np);
> +       }
> +       of_node_put(np);
> +}
> +
>  /* reduce the duplicated frequencies in frequency table */
>  static void freq_table_redup(struct cpufreq_frequency_table *freq_table,
>                 int count)
> @@ -105,6 +174,7 @@ static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
>         int i, j, ind;
>         unsigned int freq, max_freq;
>         struct cpufreq_frequency_table table;
> +
>         for (i = 0; i < count - 1; i++) {
>                 max_freq = freq_table[i].frequency;
>                 ind = i;
> @@ -129,7 +199,7 @@ static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
>         }
>  }
>
> -static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
> +static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
>  {
>         struct device_node *np;
>         int i, count, ret;
> @@ -145,10 +215,8 @@ static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
>                 return -ENODEV;
>
>         data = kzalloc(sizeof(*data), GFP_KERNEL);
> -       if (!data) {
> -               pr_err("%s: no memory\n", __func__);

Wasn't this useful ?

> +       if (!data)
>                 goto err_np;
> -       }
>
>         policy->clk = of_clk_get(np, 0);
>         if (IS_ERR(policy->clk)) {
> @@ -170,7 +238,7 @@ static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
>         }
>
>         if (fmask)
> -               mask = fmask[get_hard_smp_processor_id(cpu)];
> +               mask = fmask[get_cpu_physical_id(cpu)];
>         else
>                 mask = 0x0;
>
> @@ -201,13 +269,13 @@ static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
>         data->table = table;
>
>         /* update ->cpus if we have cluster, no harm if not */
> -       cpumask_copy(policy->cpus, per_cpu(cpu_mask, cpu));
> -       for_each_cpu(i, per_cpu(cpu_mask, cpu))
> +       set_affected_cpus(policy);
> +       for_each_cpu(i, policy->cpus)
>                 per_cpu(cpu_data, i) = data;

Get rid of this per-cpu data and use policy->driver_data instead.

>
>         /* Minimum transition latency is 12 platform clocks */
>         u64temp = 12ULL * NSEC_PER_SEC;
> -       do_div(u64temp, fsl_get_sys_freq());
> +       do_div(u64temp, get_bus_freq());
>         policy->cpuinfo.transition_latency = u64temp + 1;
>
>         of_node_put(np);
> @@ -227,7 +295,7 @@ err_np:
>         return -ENODEV;
>  }
>
> -static int __exit corenet_cpufreq_cpu_exit(struct cpufreq_policy *policy)
> +static int __exit qoriq_cpufreq_cpu_exit(struct cpufreq_policy *policy)
>  {
>         struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
>         unsigned int cpu;
> @@ -236,13 +304,13 @@ static int __exit corenet_cpufreq_cpu_exit(struct cpufreq_policy *policy)
>         kfree(data->table);
>         kfree(data);
>
> -       for_each_cpu(cpu, per_cpu(cpu_mask, policy->cpu))
> +       for_each_cpu(cpu, policy->cpus)
>                 per_cpu(cpu_data, cpu) = NULL;
>
>         return 0;
>  }
>
> -static int corenet_cpufreq_target(struct cpufreq_policy *policy,
> +static int qoriq_cpufreq_target(struct cpufreq_policy *policy,
>                 unsigned int index)
>  {
>         struct clk *parent;
> @@ -252,18 +320,18 @@ static int corenet_cpufreq_target(struct cpufreq_policy *policy,
>         return clk_set_parent(policy->clk, parent);
>  }
>
> -static struct cpufreq_driver ppc_corenet_cpufreq_driver = {
> -       .name           = "ppc_cpufreq",
> +static struct cpufreq_driver qoriq_cpufreq_driver = {
> +       .name           = "qoriq_cpufreq",
>         .flags          = CPUFREQ_CONST_LOOPS,
> -       .init           = corenet_cpufreq_cpu_init,
> -       .exit           = __exit_p(corenet_cpufreq_cpu_exit),
> +       .init           = qoriq_cpufreq_cpu_init,
> +       .exit           = __exit_p(qoriq_cpufreq_cpu_exit),
>         .verify         = cpufreq_generic_frequency_table_verify,
> -       .target_index   = corenet_cpufreq_target,
> +       .target_index   = qoriq_cpufreq_target,
>         .get            = cpufreq_generic_get,
>         .attr           = cpufreq_generic_attr,
>  };
>
> -static const struct of_device_id node_matches[] __initdata = {
> +static const struct of_device_id node_matches[] __initconst = {
>         { .compatible = "fsl,p2041-clockgen", .data = &sdata[0], },
>         { .compatible = "fsl,p3041-clockgen", .data = &sdata[0], },
>         { .compatible = "fsl,p5020-clockgen", .data = &sdata[1], },
> @@ -273,61 +341,43 @@ static const struct of_device_id node_matches[] __initdata = {
>         {}
>  };
>
> -static int __init ppc_corenet_cpufreq_init(void)
> +static int __init qoriq_cpufreq_init(void)
>  {
>         int ret;
>         struct device_node  *np;
>         const struct of_device_id *match;
>         const struct soc_data *data;
> -       unsigned int cpu;
>
>         np = of_find_matching_node(NULL, node_matches);
>         if (!np)
>                 return -ENODEV;
>
> -       for_each_possible_cpu(cpu) {
> -               if (!alloc_cpumask_var(&per_cpu(cpu_mask, cpu), GFP_KERNEL))
> -                       goto err_mask;
> -               cpumask_copy(per_cpu(cpu_mask, cpu), cpu_core_mask(cpu));
> -       }
> -
>         match = of_match_node(node_matches, np);
>         data = match->data;
>         if (data) {
>                 if (data->flag)
>                         fmask = data->freq_mask;
> -               min_cpufreq = fsl_get_sys_freq();
> +               min_cpufreq = get_bus_freq();
>         } else {
> -               min_cpufreq = fsl_get_sys_freq() / 2;
> +               min_cpufreq = get_bus_freq() / 2;
>         }
>
>         of_node_put(np);
>
> -       ret = cpufreq_register_driver(&ppc_corenet_cpufreq_driver);
> +       ret = cpufreq_register_driver(&qoriq_cpufreq_driver);
>         if (!ret)
> -               pr_info("Freescale PowerPC corenet CPU frequency scaling driver\n");
> +               pr_info("Freescale QorIQ CPU frequency scaling driver\n");
>
>         return ret;
> -
> -err_mask:
> -       for_each_possible_cpu(cpu)
> -               free_cpumask_var(per_cpu(cpu_mask, cpu));
> -
> -       return -ENOMEM;
>  }
> -module_init(ppc_corenet_cpufreq_init);
> +module_init(qoriq_cpufreq_init);
>
> -static void __exit ppc_corenet_cpufreq_exit(void)
> +static void __exit qoriq_cpufreq_exit(void)
>  {
> -       unsigned int cpu;
> -
> -       for_each_possible_cpu(cpu)
> -               free_cpumask_var(per_cpu(cpu_mask, cpu));
> -
> -       cpufreq_unregister_driver(&ppc_corenet_cpufreq_driver);
> +       cpufreq_unregister_driver(&qoriq_cpufreq_driver);
>  }
> -module_exit(ppc_corenet_cpufreq_exit);
> +module_exit(qoriq_cpufreq_exit);
>
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Tang Yuantian <Yuantian.Tang@...escale.com>");
> -MODULE_DESCRIPTION("cpufreq driver for Freescale e500mc series SoCs");
> +MODULE_DESCRIPTION("cpufreq driver for Freescale QorIQ series SoCs");

+ comments from Kumar Gala :)
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