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

Mike Turquette
2013-08-07T16:44:23Z

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