Subject: [PATCH v9 1/6] clk: samsung: add infrastructure to register cpu clocks

From: [email-masked] (Mike Turquette)
Date: Mon, 01 Sep 2014 15:29:37 -0700

Quoting Thomas Abraham (2014-07-30 01:07:38)
> The CPU clock provider supplies the clock to the CPU clock domain. The
> composition and organization of the CPU clock provider could vary among
> Exynos SoCs. A CPU clock provider can be composed of clock mux, dividers
> and gates. This patch defines a new clock type for CPU clock provider and
> adds infrastructure to register the CPU clock providers for Samsung
> platforms.
> 
> Signed-off-by: Thomas Abraham <[email-masked]>
> Reviewed-by: Tomasz Figa <[email-masked]>

Acked-by: Mike Turquette <[email-masked]>

> ---
>  drivers/clk/samsung/Makefile  |    2 +-
>  drivers/clk/samsung/clk-cpu.c |  335 +++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/samsung/clk-cpu.h |   91 +++++++++++
>  3 files changed, 427 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/clk/samsung/clk-cpu.c
>  create mode 100644 drivers/clk/samsung/clk-cpu.h
> 
> diff --git a/drivers/clk/samsung/Makefile b/drivers/clk/samsung/Makefile
> index 6fb4bc6..8909c93 100644
> --- a/drivers/clk/samsung/Makefile
> +++ b/drivers/clk/samsung/Makefile
> @@ -2,7 +2,7 @@
>  # Samsung Clock specific Makefile
>  #
>  
> -obj-$(CONFIG_COMMON_CLK)       += clk.o clk-pll.o
> +obj-$(CONFIG_COMMON_CLK)       += clk.o clk-pll.o clk-cpu.o
>  obj-$(CONFIG_SOC_EXYNOS3250)   += clk-exynos3250.o
>  obj-$(CONFIG_ARCH_EXYNOS4)     += clk-exynos4.o
>  obj-$(CONFIG_SOC_EXYNOS5250)   += clk-exynos5250.o
> diff --git a/drivers/clk/samsung/clk-cpu.c b/drivers/clk/samsung/clk-cpu.c
> new file mode 100644
> index 0000000..009a21b
> --- /dev/null
> +++ b/drivers/clk/samsung/clk-cpu.c
> @@ -0,0 +1,335 @@
> +/*
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Thomas Abraham <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This file contains the utility function to register CPU clock for Samsung
> + * Exynos platforms. A CPU clock is defined as a clock supplied to a CPU or a
> + * group of CPUs. The CPU clock is typically derived from a hierarchy of clock
> + * blocks which includes mux and divider blocks. There are a number of other
> + * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI
> + * clock for CPU domain. The rates of these auxiliary clocks are related to the
> + * CPU clock rate and this relation is usually specified in the hardware manual
> + * of the SoC or supplied after the SoC characterization.
> + *
> + * The below implementation of the CPU clock allows the rate changes of the CPU
> + * clock and the corresponding rate changes of the auxillary clocks of the CPU
> + * domain. The platform clock driver provides a clock register configuration
> + * for each configurable rate which is then used to program the clock hardware
> + * registers to acheive a fast co-oridinated rate change for all the CPU domain
> + * clocks.
> + *
> + * On a rate change request for the CPU clock, the rate change is propagated
> + * upto the PLL supplying the clock to the CPU domain clock blocks. While the
> + * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an
> + * alternate clock source. If required, the alternate clock source is divided
> + * down in order to keep the output clock rate within the previous OPP limits.
> +*/
> +
> +#include <linux/errno.h>
> +#include "clk-cpu.h"
> +
> +#define E4210_SRC_CPU          0x0
> +#define E4210_STAT_CPU         0x200
> +#define E4210_DIV_CPU0         0x300
> +#define E4210_DIV_CPU1         0x304
> +#define E4210_DIV_STAT_CPU0    0x400
> +#define E4210_DIV_STAT_CPU1    0x404
> +
> +#define E4210_DIV0_RATIO0_MASK 0x7
> +#define E4210_DIV1_HPM_MASK    (0x7 << 4)
> +#define E4210_DIV1_COPY_MASK   (0x7 << 0)
> +#define E4210_MUX_HPM_MASK     (1 << 20)
> +#define E4210_DIV0_ATB_SHIFT   16
> +#define E4210_DIV0_ATB_MASK    (DIV_MASK << E4210_DIV0_ATB_SHIFT)
> +
> +#define MAX_DIV                        8
> +#define DIV_MASK               7
> +#define DIV_MASK_ALL           0xffffffff
> +#define MUX_MASK               7
> +
> +/*
> + * Helper function to wait until divider(s) have stabilized after the divider
> + * value has changed.
> + */
> +static void wait_until_divider_stable(void __iomem *div_reg, unsigned long mask)
> +{
> +       unsigned long timeout = jiffies + msecs_to_jiffies(10);
> +
> +       do {
> +               if (!(readl(div_reg) & mask))
> +                       return;
> +       } while (time_before(jiffies, timeout));
> +
> +       pr_err("%s: timeout in divider stablization\n", __func__);
> +}
> +
> +/*
> + * Helper function to wait until mux has stabilized after the mux selection
> + * value was changed.
> + */
> +static void wait_until_mux_stable(void __iomem *mux_reg, u32 mux_pos,
> +                                       unsigned long mux_value)
> +{
> +       unsigned long timeout = jiffies + msecs_to_jiffies(10);
> +
> +       do {
> +               if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value)
> +                       return;
> +       } while (time_before(jiffies, timeout));
> +
> +       pr_err("%s: re-parenting mux timed-out\n", __func__);
> +}
> +
> +/* common round rate callback useable for all types of CPU clocks */
> +static long exynos_cpuclk_round_rate(struct clk_hw *hw,
> +                       unsigned long drate, unsigned long *prate)
> +{
> +       struct clk *parent = __clk_get_parent(hw->clk);
> +       *prate = __clk_round_rate(parent, drate);
> +       return *prate;
> +}
> +
> +/* common recalc rate callback useable for all types of CPU clocks */
> +static unsigned long exynos_cpuclk_recalc_rate(struct clk_hw *hw,
> +                       unsigned long parent_rate)
> +{
> +       /*
> +        * The CPU clock output (armclk) rate is the same as its parent
> +        * rate. Although there exist certain dividers inside the CPU
> +        * clock block that could be used to divide the parent clock,
> +        * the driver does not make use of them currently, except during
> +        * frequency transitions.
> +        */
> +       return parent_rate;
> +}
> +
> +static const struct clk_ops exynos_cpuclk_clk_ops = {
> +       .recalc_rate = exynos_cpuclk_recalc_rate,
> +       .round_rate = exynos_cpuclk_round_rate,
> +};
> +
> +/*
> + * Helper function to set the 'safe' dividers for the CPU clock. The parameters
> + * div and mask contain the divider value and the register bit mask of the
> + * dividers to be programmed.
> + */
> +static void exynos_set_safe_div(void __iomem *base, unsigned long div,
> +                                       unsigned long mask)
> +{
> +       unsigned long div0;
> +
> +       div0 = readl(base + E4210_DIV_CPU0);
> +       div0 = (div0 & ~mask) | (div & mask);
> +       writel(div0, base + E4210_DIV_CPU0);
> +       wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, mask);
> +}
> +
> +/* handler for pre-rate change notification from parent clock */
> +static int exynos_cpuclk_pre_rate_change(struct clk_notifier_data *ndata,
> +                       struct exynos_cpuclk *cpuclk, void __iomem *base)
> +{
> +       const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
> +       unsigned long alt_prate = clk_get_rate(cpuclk->alt_parent);
> +       unsigned long alt_div = 0, alt_div_mask = DIV_MASK;
> +       unsigned long div0, div1 = 0, mux_reg;
> +
> +       /* find out the divider values to use for clock data */
> +       while ((cfg_data->prate * 1000) != ndata->new_rate) {
> +               if (cfg_data->prate == 0)
> +                       return -EINVAL;
> +               cfg_data++;
> +       }
> +
> +       /*
> +        * For the selected PLL clock frequency, get the pre-defined divider
> +        * values. If the clock for sclk_hpm is not sourced from apll, then
> +        * the values for DIV_COPY and DIV_HPM dividers need not be set.
> +        */
> +       div0 = cfg_data->div0;
> +       if (test_bit(CLK_CPU_HAS_DIV1, &cpuclk->flags)) {
> +               div1 = cfg_data->div1;
> +               if (readl(base + E4210_SRC_CPU) & E4210_MUX_HPM_MASK)
> +                       div1 = readl(base + E4210_DIV_CPU1) &
> +                               (E4210_DIV1_HPM_MASK | E4210_DIV1_COPY_MASK);
> +       }
> +
> +       spin_lock(cpuclk->lock);
> +
> +       /*
> +        * If the new and old parent clock speed is less than the clock speed
> +        * of the alternate parent, then it should be ensured that at no point
> +        * the armclk speed is more than the old_prate until the dividers are
> +        * set.
> +        */
> +       if (alt_prate > ndata->old_rate) {
> +               alt_div =  DIV_ROUND_UP(alt_prate, ndata->old_rate) - 1;
> +               WARN_ON(alt_div >= MAX_DIV);
> +
> +               if (test_bit(CLK_CPU_NEEDS_DEBUG_ALT_DIV, &cpuclk->flags)) {
> +                       /*
> +                        * In Exynos4210, ATB clock parent is also mout_core. So
> +                        * ATB clock also needs to be mantained at safe speed.
> +                        */
> +                       alt_div |= E4210_DIV0_ATB_MASK;
> +                       alt_div_mask |= E4210_DIV0_ATB_MASK;
> +               }
> +               exynos_set_safe_div(base, alt_div, alt_div_mask);
> +               div0 |= alt_div;
> +       }
> +
> +       /* select sclk_mpll as the alternate parent */
> +       mux_reg = readl(base + E4210_SRC_CPU);
> +       writel(mux_reg | (1 << 16), base + E4210_SRC_CPU);
> +       wait_until_mux_stable(base + E4210_STAT_CPU, 16, 2);
> +
> +       /* alternate parent is active now. set the dividers */
> +       writel(div0, base + E4210_DIV_CPU0);
> +       wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, DIV_MASK_ALL);
> +
> +       if (test_bit(CLK_CPU_HAS_DIV1, &cpuclk->flags)) {
> +               writel(div1, base + E4210_DIV_CPU1);
> +               wait_until_divider_stable(base + E4210_DIV_STAT_CPU1,
> +                               DIV_MASK_ALL);
> +       }
> +
> +       spin_unlock(cpuclk->lock);
> +       return 0;
> +}
> +
> +/* handler for post-rate change notification from parent clock */
> +static int exynos_cpuclk_post_rate_change(struct clk_notifier_data *ndata,
> +                       struct exynos_cpuclk *cpuclk, void __iomem *base)
> +{
> +       const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
> +       unsigned long div = 0, div_mask = DIV_MASK;
> +       unsigned long mux_reg;
> +
> +       spin_lock(cpuclk->lock);
> +
> +       /* select mout_apll as the alternate parent */
> +       mux_reg = readl(base + E4210_SRC_CPU);
> +       writel(mux_reg & ~(1 << 16), base + E4210_SRC_CPU);
> +       wait_until_mux_stable(base + E4210_STAT_CPU, 16, 1);
> +
> +       if (test_bit(CLK_CPU_NEEDS_DEBUG_ALT_DIV, &cpuclk->flags)) {
> +               /* find out the divider values to use for clock data */
> +               while ((cfg_data->prate * 1000) != ndata->new_rate) {
> +                       if (cfg_data->prate == 0)
> +                               return -EINVAL;
> +                       cfg_data++;
> +               }
> +
> +               div |= (cfg_data->div0 & E4210_DIV0_ATB_MASK);
> +               div_mask |= E4210_DIV0_ATB_MASK;
> +       }
> +
> +       exynos_set_safe_div(base, div, div_mask);
> +       spin_unlock(cpuclk->lock);
> +       return 0;
> +}
> +
> +/*
> + * This notifier function is called for the pre-rate and post-rate change
> + * notifications of the parent clock of cpuclk.
> + */
> +static int exynos_cpuclk_notifier_cb(struct notifier_block *nb,
> +                               unsigned long event, void *data)
> +{
> +       struct clk_notifier_data *ndata = data;
> +       struct exynos_cpuclk *cpuclk;
> +       void __iomem *base;
> +       int err = 0;
> +
> +       cpuclk = container_of(nb, struct exynos_cpuclk, clk_nb);
> +       base = cpuclk->ctrl_base;
> +
> +       if (event == PRE_RATE_CHANGE)
> +               err = exynos_cpuclk_pre_rate_change(ndata, cpuclk, base);
> +       else if (event == POST_RATE_CHANGE)
> +               err = exynos_cpuclk_post_rate_change(ndata, cpuclk, base);
> +
> +       return notifier_from_errno(err);
> +}
> +
> +/* helper function to register a CPU clock */
> +int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
> +               unsigned int lookup_id, const char *name, const char *parent,
> +               const char *alt_parent, unsigned long offset,
> +               const struct exynos_cpuclk_cfg_data *cfg,
> +               unsigned long num_cfgs, unsigned long flags)
> +{
> +       struct exynos_cpuclk *cpuclk;
> +       struct clk_init_data init;
> +       struct clk *clk;
> +       int ret = 0;
> +
> +       cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
> +       if (!cpuclk)
> +               return -ENOMEM;
> +
> +       init.name = name;
> +       init.flags = CLK_SET_RATE_PARENT;
> +       init.parent_names = &parent;
> +       init.num_parents = 1;
> +       init.ops = &exynos_cpuclk_clk_ops;
> +
> +       cpuclk->hw.init = &init;
> +       cpuclk->ctrl_base = ctx->reg_base + offset;
> +       cpuclk->lock = &ctx->lock;
> +       cpuclk->flags = flags;
> +       cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb;
> +
> +       cpuclk->alt_parent = __clk_lookup(alt_parent);
> +       if (!cpuclk->alt_parent) {
> +               pr_err("%s: could not lookup alternate parent %s\n",
> +                               __func__, alt_parent);
> +               ret = -EINVAL;
> +               goto free_cpuclk;
> +       }
> +
> +       clk = __clk_lookup(parent);
> +       if (!clk) {
> +               pr_err("%s: could not lookup parent clock %s\n",
> +                               __func__, parent);
> +               ret = -EINVAL;
> +               goto free_cpuclk;
> +       }
> +
> +       ret = clk_notifier_register(clk, &cpuclk->clk_nb);
> +       if (ret) {
> +               pr_err("%s: failed to register clock notifier for %s\n",
> +                               __func__, name);
> +               goto free_cpuclk;
> +       }
> +
> +       cpuclk->cfg = kmemdup(cfg, sizeof(*cfg) * num_cfgs, GFP_KERNEL);
> +       if (!cpuclk->cfg) {
> +               pr_err("%s: could not allocate memory for cpuclk data\n",
> +                               __func__);
> +               kfree(cpuclk);
> +               ret = -ENOMEM;
> +               goto unregister_clk_nb;
> +       }
> +
> +       clk = clk_register(NULL, &cpuclk->hw);
> +       if (IS_ERR(clk)) {
> +               pr_err("%s: could not register cpuclk %s\n", __func__,  name);
> +               ret = PTR_ERR(clk);
> +               goto free_cpuclk_data;
> +       }
> +
> +       samsung_clk_add_lookup(ctx, clk, lookup_id);
> +       return 0;
> +
> +free_cpuclk_data:
> +       kfree(cpuclk->cfg);
> +unregister_clk_nb:
> +       clk_notifier_unregister(__clk_lookup(parent), &cpuclk->clk_nb);
> +free_cpuclk:
> +       kfree(cpuclk);
> +       return ret;
> +}
> diff --git a/drivers/clk/samsung/clk-cpu.h b/drivers/clk/samsung/clk-cpu.h
> new file mode 100644
> index 0000000..42e1905
> --- /dev/null
> +++ b/drivers/clk/samsung/clk-cpu.h
> @@ -0,0 +1,91 @@
> +/*
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Common Clock Framework support for all PLL's in Samsung platforms
> +*/
> +
> +#ifndef __SAMSUNG_CLK_CPU_H
> +#define __SAMSUNG_CLK_CPU_H
> +
> +#include "clk.h"
> +
> +#define E4210_CPU_DIV0(apll, pclk_dbg, atb, periph, corem1, corem0)    \
> +               (((apll) << 24) | ((pclk_dbg) << 20) | ((atb) << 16) |  \
> +               ((periph) << 12) | ((corem1) << 8) | ((corem0) <<  4))
> +#define E4210_CPU_DIV1(hpm, copy)                                      \
> +               (((hpm) << 4) | ((copy) << 0))
> +
> +#define E5250_CPU_DIV0(apll, pclk_dbg, atb, periph, acp, cpud)         \
> +               ((((apll) << 24) | ((pclk_dbg) << 20) | ((atb) << 16) | \
> +                ((periph) << 12) | ((acp) << 8) | ((cpud) << 4)))
> +#define E5250_CPU_DIV1(hpm, copy)                                      \
> +               (((hpm) << 4) | (copy))
> +
> +#define E5420_EGL_DIV0(apll, pclk_dbg, atb, cpud)                      \
> +               ((((apll) << 24) | ((pclk_dbg) << 20) | ((atb) << 16) | \
> +                ((cpud) << 4)))
> +#define E5420_KFC_DIV(kpll, pclk, aclk)                                        \
> +               ((((kpll) << 24) | ((pclk) << 20) | ((aclk) << 4)))
> +
> +/**
> + * struct exynos_cpuclk_data: config data to setup cpu clocks.
> + * @prate: frequency of the primary parent clock (in KHz).
> + * @div0: value to be programmed in the div_cpu0 register.
> + * @div1: value to be programmed in the div_cpu1 register.
> + *
> + * This structure holds the divider configuration data for dividers in the CPU
> + * clock domain. The parent frequency at which these divider values are valid is
> + * specified in @prate. The @prate is the frequency of the primary parent clock.
> + * For CPU clock domains that do not have a DIV1 register, the @div1 member
> + * value is not used.
> + */
> +struct exynos_cpuclk_cfg_data {
> +       unsigned long   prate;
> +       unsigned long   div0;
> +       unsigned long   div1;
> +};
> +
> +/**
> + * struct exynos_cpuclk: information about clock supplied to a CPU core.
> + * @hw:        handle between CCF and CPU clock.
> + * @alt_parent: alternate parent clock to use when switching the speed
> + *     of the primary parent clock.
> + * @ctrl_base: base address of the clock controller.
> + * @lock: cpu clock domain register access lock.
> + * @cfg: cpu clock rate configuration data.
> + * @num_cfgs: number of array elements in @cfg array.
> + * @clk_nb: clock notifier registered for changes in clock speed of the
> + *     primary parent clock.
> + * @flags: configuration flags for the CPU clock.
> + *
> + * This structure holds information required for programming the CPU clock for
> + * various clock speeds.
> + */
> +struct exynos_cpuclk {
> +       struct clk_hw                           hw;
> +       struct clk                              *alt_parent;
> +       void __iomem                            *ctrl_base;
> +       spinlock_t                              *lock;
> +       const struct exynos_cpuclk_cfg_data     *cfg;
> +       const unsigned long                     num_cfgs;
> +       struct notifier_block                   clk_nb;
> +       unsigned long                           flags;
> +
> +/* The CPU clock registers has DIV1 configuration register */
> +#define CLK_CPU_HAS_DIV1               (1 << 0)
> +/* When ALT parent is active, debug clocks need safe divider values */
> +#define CLK_CPU_NEEDS_DEBUG_ALT_DIV    (1 << 1)
> +};
> +
> +extern int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
> +                       unsigned int lookup_id, const char *name,
> +                       const char *parent, const char *alt_parent,
> +                       unsigned long offset,
> +                       const struct exynos_cpuclk_cfg_data *cfg,
> +                       unsigned long num_cfgs, unsigned long flags);
> +
> +#endif /* __SAMSUNG_CLK_CPU_H */
> -- 
> 1.7.9.5
>