Re: [PATCH v2 2/7] clk: samsung: add infrastructure to register cpu clocks

Lukasz Majewski
2014-01-20T08:24:12Z

Hi Thomas,

> From: Thomas Abraham <thomas.ab@samsung.com>
>
> 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.
>
> In addition to this, the arm cpu clock provider for Exynos4210 and
> compatible SoCs is instantiated using the new cpu clock type. The
> clock frequency table and the clock configuration data for this clock
> is obtained from device tree. This implementation is reusable for
> Exynos4x12 and Exynos5250 SoCs as well.
>
> Cc: Tomasz Figa <t.figa@samsung.com>
> Cc: Lukasz Majewski <l.majewski@majess.pl>
> Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
> ---
> drivers/clk/samsung/Makefile | 2 +-
> drivers/clk/samsung/clk-cpu.c | 345
> +++++++++++++++++++++++++++++++++++++++++
> drivers/clk/samsung/clk.h | 3 + 3 files changed, 349
> insertions(+), 1 deletions(-) create mode 100644
> drivers/clk/samsung/clk-cpu.c
>
> diff --git a/drivers/clk/samsung/Makefile
> b/drivers/clk/samsung/Makefile index 8eb4799..e2b453f 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-$(CONFIG_ARCH_EXYNOS4) += clk-exynos4.o
> obj-$(CONFIG_SOC_EXYNOS5250) += clk-exynos5250.o
> obj-$(CONFIG_SOC_EXYNOS5420) += clk-exynos5420.o
> diff --git a/drivers/clk/samsung/clk-cpu.c
> b/drivers/clk/samsung/clk-cpu.c new file mode 100644
> index 0000000..92fba45
> --- /dev/null
> +++ b/drivers/clk/samsung/clk-cpu.c
> @@ -0,0 +1,345 @@
> +/*
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Thomas Abraham <thomas.ab@samsung.com>
> + *
> + * 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 functions to register the cpu
> clocks
> + * for samsung platforms.
> +*/
> +
> +#include <linux/errno.h>
> +#include "clk.h"
> +
> +#define SRC_CPU 0x0
> +#define STAT_CPU 0x200
> +#define DIV_CPU0 0x300
> +#define DIV_CPU1 0x304
> +#define DIV_STAT_CPU0 0x400
> +#define DIV_STAT_CPU1 0x404
> +
> +/**
> + * struct samsung_cpuclk_freq_table: table of frequency supported by
> + * a cpu clock and associated data if any.
> + * @freq: points to a table of supported frequencies (in KHz)
> + * @freq_count: number of entries in the frequency table
> + * @data: cpu clock specific data, if any
> + *
> + * This structure holds the frequency options supported by the cpu
> clock in
> + * which this structure is contained. The data pointer is an
> optional data
> + * that can provide any additional configuration options for the
> supported
> + * frequencies. This structure is intended to be reusable for all
> cpu clocks
> + * in Samsung SoC based platforms
> + */
> +struct samsung_cpuclk_freq_table {
> + const unsigned long *freq; /* in KHz */
> + unsigned long freq_count;
> + const void *data;
> +};
> +
> +/**
> + * struct exynos4210_freq_data: format of auxillary data associated
> with
> + * each frequency supported by the cpu clock for exynos4210.
> + * @parent_freq: The frequency of the parent clock required to
> generate the
> + * supported cpu clock speed.
> + * @div0: value to be programmed in the div_cpu0 register.
> + * @div1: value to be programmed in the div_cpu1 register.
> + *
> + * This structure holds the auxillary configuration data for each
> supported
> + * cpu clock frequency on Exynos4210 and compatible SoCs.
> + */
> +struct exynos4210_freq_data {
> + unsigned long parent_freq;
> + unsigned int div0;
> + unsigned int div1;
> +};
> +
> +/**
> + * struct samsung_cpuclk: information about clock supplied to a CPU
> core.
> + * @hw: handle between ccf and cpu clock.
> + * @ctrl_base: base address of the clock controller.
> + * @offset: offset from the ctrl_base address where the cpu clock
> div/mux
> + * registers can be accessed.
> + * @parent: clock handle representing the clock output of the parent
> clock.
> + * @freq_table: the frequency table supported by this cpu clock.
> + */
> +struct samsung_cpuclk {
> + struct clk_hw hw;
> + void __iomem *ctrl_base;
> + unsigned long offset;
> + struct clk *parent;
> + const struct samsung_cpuclk_freq_table *freq_table;
> +};
> +
> +#define to_samsung_cpuclk(hw) container_of(hw, struct
> samsung_cpuclk, hw) +
> +/**
> + * struct samsung_cpuclk_match_data: soc specific data for cpu
> clocks.
> + * @parser: pointer to a function that can parse SoC specific cpu
> clock
> + * frequency and associated configuration data.
> + * @offset: optional offset from base of clock controller register
> base,
> + * to be used when accessing clock controller registers
> related to the
> + * cpu clock.
> + * @offset: offset from the ctrl_base address where the cpu clock
> div/mux
> + * registers can be accessed.
> + */
> +struct samsung_cpuclk_match_data {
> + int (*parser)(struct device_node *,
> + struct samsung_cpuclk_freq_table **);
> + unsigned int offset;
> +};
> +
> +/* This is a helper function to perform clock rounding for cpu
> clocks. */ +static long samsung_cpuclk_round_rate(struct clk_hw *hw,
> + unsigned long drate, unsigned long *prate)
> +{
> + struct samsung_cpuclk *cpuclk = to_samsung_cpuclk(hw);
> + const struct samsung_cpuclk_freq_table *freq_tbl;
> + int i;
> +
> + freq_tbl = cpuclk->freq_table;
> + drate /= 1000;
> +
> + for (i = 0; i < freq_tbl->freq_count; i++) {
> + if (drate >= freq_tbl->freq[i])
> + return freq_tbl->freq[i] * 1000;
> + }
> + return freq_tbl->freq[i - 1] * 1000;
> +}
> +
> +#define EXYNOS4210_ARM_DIV1(base) ((readl(base + DIV_CPU0) & 0xf) +
> 1) +#define EXYNOS4210_ARM_DIV2(base) (((readl(base + DIV_CPU0) >>
> 28) & 0xf) + 1) +
> +/*
> + * CPU clock speed for Exynos4210 and compatible SoCs is
> + * parent clock speed / core1_ratio / core2_ratio
> + */
> +static unsigned long exynos4210_armclk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct samsung_cpuclk *armclk = to_samsung_cpuclk(hw);
> + void __iomem *base = armclk->ctrl_base + armclk->offset;
> +
> + return parent_rate / EXYNOS4210_ARM_DIV1(base) /
> + EXYNOS4210_ARM_DIV2(base);
> +}
> +
> +/* set rate callback for cpuclk type on Exynos4210 and similar SoCs
> */ +static int exynos4210_armclk_set_rate(struct clk_hw *hw, unsigned
> long drate,
> + unsigned long prate)
> +{
> + struct samsung_cpuclk *armclk = to_samsung_cpuclk(hw);
> + const struct samsung_cpuclk_freq_table *freq_tbl;
> + const struct exynos4210_freq_data *freq_data;
> + unsigned long mux_reg, idx;
> + void __iomem *base;
> +
> + if (drate == prate)
> + return 0;
> +
> + freq_tbl = armclk->freq_table;
> + freq_data = freq_tbl->data;
> + base = armclk->ctrl_base + armclk->offset;
> +
> + for (idx = 0; idx < freq_tbl->freq_count; idx++, freq_data++)
> + if ((freq_tbl->freq[idx] * 1000) == drate)
> + break;
> +
> + if (drate < prate) {
> + mux_reg = readl(base + SRC_CPU);
> + writel(mux_reg | (1 << 16), base + SRC_CPU);
> + while (((readl(base + STAT_CPU) >> 16) & 0x7) != 2)
> + ;
> +
> + clk_set_rate(armclk->parent, drate);
> + }
> +
> + writel(freq_data->div0, base + DIV_CPU0);
> + while (readl(base + DIV_STAT_CPU0) != 0)
> + ;
> + writel(freq_data->div1, base + DIV_CPU1);
> + while (readl(base + DIV_STAT_CPU1) != 0)
> + ;
> +
> + if (drate > prate) {
> + mux_reg = readl(base + SRC_CPU);
> + writel(mux_reg | (1 << 16), base + SRC_CPU);
> + while (((readl(base + STAT_CPU) >> 16) & 0x7) != 2)
> + ;
> +
> + clk_set_rate(armclk->parent, freq_data->parent_freq
> * 1000);
> + }
> +
> + mux_reg = readl(base + SRC_CPU);
> + writel(mux_reg & ~(1 << 16), base + SRC_CPU);
> + while (((readl(base + STAT_CPU) >> 16) & 0x7) != 1)
> + ;
> + return 0;
> +}
> +
> +/* clock ops for armclk on Exynos4210 and compatible platforms. */
> +static const struct clk_ops exynos4210_armclk_clk_ops = {
> + .recalc_rate = exynos4210_armclk_recalc_rate,
> + .round_rate = samsung_cpuclk_round_rate,
> + .set_rate = exynos4210_armclk_set_rate,
> +};
> +
> +/* helper function to register a cpu clock */
> +static void __init samsung_cpuclk_register(unsigned int lookup_id,
> + const char *name, const char *parent, const struct
> clk_ops *ops,
> + const struct samsung_cpuclk_freq_table *freq_tbl,
> + void __iomem *reg_base,
> + const struct samsung_cpuclk_match_data *data)
> +{
> + struct samsung_cpuclk *cpuclk;
> + struct clk_init_data init;
> + struct clk *clk;
> +
> + cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
> + if (!cpuclk) {
> + pr_err("%s: could not allocate memory for cpuclk
> %s\n",
> + __func__, name);
> + return;
> + }
> +
> + init.name = name;
> + init.flags = CLK_GET_RATE_NOCACHE;
> + init.parent_names = &parent;
> + init.num_parents = 1;
> + init.ops = ops;
> +
> + cpuclk->hw.init = &init;
> + cpuclk->ctrl_base = reg_base;
> + cpuclk->offset = data->offset;
> + cpuclk->freq_table = freq_tbl;
> + cpuclk->parent = __clk_lookup(parent);
> +
> + clk = clk_register(NULL, &cpuclk->hw);
> + if (IS_ERR(clk)) {
> + pr_err("%s: could not register cpuclk %s\n",
> __func__, name);
> + kfree(cpuclk);
> + return;
> + }
> + samsung_clk_add_lookup(clk, lookup_id);
> +}
> +
> +#define EXYNOS4210_DIV_CPU01(d0, d1, d2, d3, d4, d5, d6,
> d7) \
> + ((d0 << 28) | (d1 << 24) | (d2 << 20) | (d3
> << 16) | \
> + (d4 << 12) | (d5 << 8) | (d6 << 4) | (d7 << 0))
> +#define EXYNOS4210_DIV_CPU11(d0, d1,
> d2) \
> + ((d0 << 8) | (d1 << 4) | (d2 << 0))
> +#define EXYNOS4210_CFG_LEN 13
> +
> +/*
> + * parse cpu clock frequency table and auxillary configuration data
> from dt
> + * for exynos4210 and compatible SoC's.
> + */
> +static int exynos4210_armclk_cfg_parser(struct device_node *np,
> + struct samsung_cpuclk_freq_table **tbl)
> +{
> + struct samsung_cpuclk_freq_table *freq_tbl;
> + struct exynos4210_freq_data *fdata, *t_fdata;
> + unsigned long *freqs, cfg[EXYNOS4210_CFG_LEN];
> + const struct property *prop;
> + unsigned int tbl_sz, i, j;
> + const __be32 *val;
> + int ret;
> +
> + prop = of_find_property(np, "arm-frequency-table", NULL);
> + if (!prop)
> + return -EINVAL;
> + if (!prop->value)
> + return -EINVAL;
> + if ((prop->length / sizeof(u32)) % EXYNOS4210_CFG_LEN)

Cannot we have the EXYNOS4210_CFG_LEN parsed from DT as well?

> + return -EINVAL;
> + tbl_sz = (prop->length / sizeof(u32)) / EXYNOS4210_CFG_LEN;
> +
> + freq_tbl = kzalloc(sizeof(*freq_tbl), GFP_KERNEL);
> + if (!freq_tbl)
> + return -ENOMEM;
> +
> + freqs = kzalloc(sizeof(u32) * tbl_sz, GFP_KERNEL);
> + if (!freqs) {
> + ret = -ENOMEM;
> + goto free_freq_tbl;
> + }
> +
> + fdata = kzalloc(sizeof(*fdata) * tbl_sz, GFP_KERNEL);
> + if (!fdata) {
> + ret = -ENOMEM;
> + goto free_freqs;
> + }
> + t_fdata = fdata;
> +
> + val = prop->value;
> + for (i = 0; i < tbl_sz; i++, fdata++) {
> + for (j = 0; j < EXYNOS4210_CFG_LEN; j++)
> + cfg[j] = be32_to_cpup(val++);
> + freqs[i] = cfg[0];
> + fdata->parent_freq = cfg[1];

Why do we need the separate parent_freq entry here?

In the patch 4/7 the freqs (cfg[0]) and parent_freq (cfg[1]) values are
the same for all supported devices (at "arm-frequency-table").

What is the rationale for having those values duplicated in the DT?

> + fdata->div0 = EXYNOS4210_DIV_CPU01(cfg[9], cfg[8],
> cfg[7],
> + cfg[6], cfg[5], cfg[4], cfg[3],
> cfg[2]);
> + fdata->div1 = EXYNOS4210_DIV_CPU11(cfg[12], cfg[11],
> cfg[10]);
> + }
> +
> + freq_tbl->freq = freqs;
> + freq_tbl->freq_count = tbl_sz;
> + freq_tbl->data = t_fdata;
> + *tbl = freq_tbl;
> + return 0;
> +
> +free_freqs:
> + kfree(freqs);
> +free_freq_tbl:
> + kfree(freq_tbl);
> + return ret;
> +}
> +
> +static struct samsung_cpuclk_match_data exynos4210_cpuclk_match_data
> = {
> + .parser = exynos4210_armclk_cfg_parser,
> + .offset = 0x14200,
> +};
> +
> +static struct samsung_cpuclk_match_data exynos5250_cpuclk_match_data
> = {
> + .parser = exynos4210_armclk_cfg_parser,
> + .offset = 0x200,
> +};
> +
> +static const struct of_device_id samsung_clock_ids[] = {
> + { .compatible = "samsung,exynos4210-clock",
> + .data = &exynos4210_cpuclk_match_data, },
> + { .compatible = "samsung,exynos4412-clock",
> + .data = &exynos4210_cpuclk_match_data, },
> + { .compatible = "samsung,exynos5250-clock",
> + .data = &exynos5250_cpuclk_match_data, },
> +};
> +
> +int __init samsung_register_arm_clock(struct device_node *np,
> + unsigned int lookup_id, const char *parent,
> void __iomem *base) +{
> + const struct of_device_id *match;
> + struct samsung_cpuclk_freq_table *freq_table;
> + const struct samsung_cpuclk_match_data *data;
> + int ret;
> +
> + match = of_match_node(samsung_clock_ids, np);
> + if (!match) {
> + pr_err("%s: could not determine soc type\n",
> __func__);
> + return -EINVAL;
> + }
> +
> + data = match->data;
> + ret = data->parser(np, &freq_table);
> + if (ret) {
> + pr_err("%s: error %d in parsing arm clock freq
> table",
> + __func__, ret);
> + return -EINVAL;
> + }
> +
> + samsung_cpuclk_register(lookup_id, "armclk", parent,
> + &exynos4210_armclk_clk_ops, freq_table, base, data);
> +
> + return 0;
> +}
> diff --git a/drivers/clk/samsung/clk.h b/drivers/clk/samsung/clk.h
> index 31b4174..a759330 100644
> --- a/drivers/clk/samsung/clk.h
> +++ b/drivers/clk/samsung/clk.h
> @@ -340,4 +340,7 @@ extern void __init
> samsung_clk_register_pll(struct samsung_pll_clock *pll_list,
> extern unsigned long _get_rate(const char *clk_name);
>
> +extern int __init samsung_register_arm_clock(struct device_node *np,
> + unsigned int lookup_id, const char *parent, void
> __iomem *base); +
> #endif /* __SAMSUNG_CLK_H */

--
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group