Re: [PATCH 1/6] clk: Tegra: Add CPU0 clock driver

[Mike Turquette <mturquette@linaro.org>]

Quoting Viresh Kumar (2013-08-07 07:46:43)
> This patch adds CPU0's clk driver for Tegra. It will be used by the generic
> cpufreq-cpu0 driver to get/set cpu clk.
> 
> Most of the platform specific bits are picked from tegra-cpufreq.c.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Hi Viresh,

It is nice to see more CPUfreq consolidation.

I'm currently hacking on a patch to introduce clk_coordinate_rates().
That function may be a better fit for this sort of thing compared to
overloading the .set_rate callback. I'll try to get the patches on the
list ASAP and will Cc you.

Regards,
Mike

> ---
>  drivers/clk/tegra/Makefile      |   1 +
>  drivers/clk/tegra/clk-cpu.c     | 164 ++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/tegra/clk-tegra30.c |   4 +
>  include/linux/clk/tegra.h       |   1 +
>  4 files changed, 170 insertions(+)
>  create mode 100644 drivers/clk/tegra/clk-cpu.c
> 
> diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
> index f49fac2..0e818c0 100644
> --- a/drivers/clk/tegra/Makefile
> +++ b/drivers/clk/tegra/Makefile
> @@ -10,3 +10,4 @@ obj-y                                 += clk-super.o
>  obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += clk-tegra20.o
>  obj-$(CONFIG_ARCH_TEGRA_3x_SOC)         += clk-tegra30.o
>  obj-$(CONFIG_ARCH_TEGRA_114_SOC)       += clk-tegra114.o
> +obj-$(CONFIG_GENERIC_CPUFREQ_CPU0)     += clk-cpu.o
> diff --git a/drivers/clk/tegra/clk-cpu.c b/drivers/clk/tegra/clk-cpu.c
> new file mode 100644
> index 0000000..01716d6
> --- /dev/null
> +++ b/drivers/clk/tegra/clk-cpu.c
> @@ -0,0 +1,164 @@
> +/*
> + * Copyright (C) 2013 Linaro
> + *
> + * Author: Viresh Kumar <viresh.kumar@linaro.org>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +/*
> + * Responsible for setting cpu0 clk as requested by cpufreq-cpu0 driver
> + *
> + * All platform specific bits are taken from tegra-cpufreq driver.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +
> +#define to_clk_cpu0(_hw) container_of(_hw, struct clk_cpu0, hw)
> +
> +struct clk_cpu0 {
> +       struct clk_hw hw;
> +       spinlock_t *lock;
> +};
> +
> +static struct clk *cpu_clk;
> +static struct clk *pll_x_clk;
> +static struct clk *pll_p_clk;
> +static struct clk *emc_clk;
> +
> +static unsigned long cpu0_recalc_rate(struct clk_hw *hw,
> +               unsigned long parent_rate)
> +{
> +       return clk_get_rate(cpu_clk);
> +}
> +
> +static long cpu0_round_rate(struct clk_hw *hw, unsigned long drate,
> +               unsigned long *parent_rate)
> +{
> +       return clk_round_rate(cpu_clk, drate);
> +}
> +
> +static int cpu0_set_rate(struct clk_hw *hw, unsigned long rate,
> +               unsigned long parent_rate)
> +{
> +       int ret;
> +
> +       /*
> +        * Vote on memory bus frequency based on cpu frequency
> +        * This sets the minimum frequency, display or avp may request higher
> +        */
> +       if (rate >= 816000000)
> +               clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
> +       else if (rate >= 456000000)
> +               clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
> +       else
> +               clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */
> +
> +       /*
> +        * Take an extra reference to the main pll so it doesn't turn
> +        * off when we move the cpu off of it
> +        */
> +       clk_prepare_enable(pll_x_clk);
> +
> +       ret = clk_set_parent(cpu_clk, pll_p_clk);
> +       if (ret) {
> +               pr_err("%s: Failed to switch cpu to clock pll_p\n", __func__);
> +               goto out;
> +       }
> +
> +       if (rate == clk_get_rate(pll_p_clk))
> +               goto out;
> +
> +       ret = clk_set_rate(pll_x_clk, rate);
> +       if (ret) {
> +               pr_err("Failed to change pll_x to %lu\n", rate);
> +               goto out;
> +       }
> +
> +       ret = clk_set_parent(cpu_clk, pll_x_clk);
> +       if (ret) {
> +               pr_err("Failed to switch cpu to clock pll_x\n");
> +               goto out;
> +       }
> +
> +out:
> +       clk_disable_unprepare(pll_x_clk);
> +       return ret;
> +}
> +
> +static struct clk_ops clk_cpu0_ops = {
> +       .recalc_rate = cpu0_recalc_rate,
> +       .round_rate = cpu0_round_rate,
> +       .set_rate = cpu0_set_rate,
> +};
> +
> +struct clk *tegra_clk_register_cpu0(void)
> +{
> +       struct clk_init_data init;
> +       struct clk_cpu0 *cpu0;
> +       struct clk *clk;
> +
> +       cpu0 = kzalloc(sizeof(*cpu0), GFP_KERNEL);
> +       if (!cpu0) {
> +               pr_err("%s: could not allocate cpu0 clk\n", __func__);
> +               return ERR_PTR(-ENOMEM);
> +       }
> +
> +       cpu_clk = clk_get_sys(NULL, "cpu");
> +       if (IS_ERR(cpu_clk)) {
> +               clk = cpu_clk;
> +               goto free_mem;
> +       }
> +
> +       pll_x_clk = clk_get_sys(NULL, "pll_x");
> +       if (IS_ERR(pll_x_clk)) {
> +               clk = pll_x_clk;
> +               goto put_cpu_clk;
> +       }
> +
> +       pll_p_clk = clk_get_sys(NULL, "pll_p_cclk");
> +       if (IS_ERR(pll_p_clk)) {
> +               clk = pll_p_clk;
> +               goto put_pll_x_clk;
> +       }
> +
> +       emc_clk = clk_get_sys("cpu", "emc");
> +       if (IS_ERR(emc_clk)) {
> +               clk = emc_clk;
> +               goto put_pll_p_clk;
> +       }
> +
> +       cpu0->hw.init = &init;
> +
> +       init.name = "cpu0";
> +       init.ops = &clk_cpu0_ops;
> +       init.flags = CLK_IS_ROOT | CLK_GET_RATE_NOCACHE;
> +       init.num_parents = 0;
> +
> +       clk = clk_register(NULL, &cpu0->hw);
> +       if (!IS_ERR(clk))
> +               return clk;
> +
> +       clk_prepare_enable(emc_clk);
> +       clk_prepare_enable(cpu_clk);
> +
> +       clk_put(emc_clk);
> +put_pll_p_clk:
> +       clk_put(pll_p_clk);
> +put_pll_x_clk:
> +       clk_put(pll_x_clk);
> +put_cpu_clk:
> +       clk_put(cpu_clk);
> +free_mem:
> +       kfree(cpu0);
> +
> +       pr_err("%s: clk register failed\n", __func__);
> +
> +       return NULL;
> +}
> diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c
> index e2c6ca0..1cabeea 100644
> --- a/drivers/clk/tegra/clk-tegra30.c
> +++ b/drivers/clk/tegra/clk-tegra30.c
> @@ -1396,6 +1396,10 @@ static void __init tegra30_super_clk_init(void)
>                                         CLK_SET_RATE_PARENT, 1, 2);
>         clk_register_clkdev(clk, "twd", NULL);
>         clks[twd] = clk;
> +
> +       /* cpu0 clk for cpufreq driver */
> +       clk = tegra_clk_register_cpu0();
> +       clk_register_clkdev(clk, NULL, "cpu0");
>  }
>  
>  static const char *mux_pllacp_clkm[] = { "pll_a_out0", "unused", "pll_p",
> diff --git a/include/linux/clk/tegra.h b/include/linux/clk/tegra.h
> index 23a0cee..d416138 100644
> --- a/include/linux/clk/tegra.h
> +++ b/include/linux/clk/tegra.h
> @@ -128,5 +128,6 @@ static inline void tegra_periph_reset_deassert(struct clk *c) {}
>  static inline void tegra_periph_reset_assert(struct clk *c) {}
>  #endif
>  void tegra_clocks_apply_init_table(void);
> +struct clk *tegra_clk_register_cpu0(void);
>  
>  #endif /* __LINUX_CLK_TEGRA_H_ */
> -- 
> 1.7.12.rc2.18.g61b472e