On 10-11-16, 15:56, Markus Mayer wrote:
> From: Markus Mayer <mma...@broadcom.com>
>
> This CPUfreq driver provides basic frequency scaling for older Broadcom
> STB SoCs that do not use AVS firmware with DVFS support. There is no
> support for voltage scaling.
>
> Signed-off-by: Markus Mayer <mma...@broadcom.com>
> ---
>
> This patch is based on Rafael's "bleeding-edge" branch.
>
> drivers/cpufreq/Kconfig.arm | 12 ++
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/brcmstb-cpufreq.c | 407
> ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 420 insertions(+)
> create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 920c469..36422af 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -33,6 +33,18 @@ config ARM_BRCMSTB_AVS_CPUFREQ_DEBUG
>
> If in doubt, say N.
>
> +config ARM_BRCMSTB_CPUFREQ
> + tristate "Broadcom STB CPUfreq driver"
> + depends on ARCH_BRCMSTB || COMPILE_TEST
> + default y
> + help
> + Some Broadcom SoCs offer multiple operating frequencies that CPUfreq
> + can take advantage of to improve energy efficiency.
> +
> + Say Y, if you have a supported Broadcom SoC. If your Broadcom SoC
> + has AVS firmware with support for frequency and voltage scaling,
> + say N here and enable ARM_BRCMSTB_AVS_CPUFREQ instead.
> +
> config ARM_DT_BL_CPUFREQ
> tristate "Generic probing via DT for ARM big LITTLE CPUfreq driver"
> depends on ARM_BIG_LITTLE_CPUFREQ && OF
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 1e46c39..23700aa 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -52,6 +52,7 @@ obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ) +=
> arm_big_little.o
> obj-$(CONFIG_ARM_DT_BL_CPUFREQ) += arm_big_little_dt.o
>
> obj-$(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ) += brcmstb-avs-cpufreq.o
> +obj-$(CONFIG_ARM_BRCMSTB_CPUFREQ) += brcmstb-cpufreq.o
> obj-$(CONFIG_ARCH_DAVINCI) += davinci-cpufreq.o
> obj-$(CONFIG_UX500_SOC_DB8500) += dbx500-cpufreq.o
> obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ) += exynos5440-cpufreq.o
> diff --git a/drivers/cpufreq/brcmstb-cpufreq.c
> b/drivers/cpufreq/brcmstb-cpufreq.c
> new file mode 100644
> index 0000000..419638a
> --- /dev/null
> +++ b/drivers/cpufreq/brcmstb-cpufreq.c
> @@ -0,0 +1,407 @@
> +/*
> + * CPU frequency scaling for Broadcom set top box SoCs
> + *
> + * Copyright (c) 2016 Broadcom
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/cpufreq.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +
> +#define BRCMSTB_CPUFREQ_PREFIX "brcmstb"
> +#define BRCMSTB_CPUFREQ_NAME BRCMSTB_CPUFREQ_PREFIX "-cpufreq"
> +
> +/* We search for these compatible strings. */
> +#define BRCMSTB_DT_CPU_CLK_CTRL "brcm,brcmstb-cpu-clk-div"
> +#define BRCMSTB_DT_MEMC_DDR "brcm,brcmstb-memc-ddr"
> +#define BRCM_AVS_CPU_DATA "brcm,avs-cpu-data-mem"
> +
> +/* We also need a few clocks in device tree. These are node names. */
> +#define BRCMSTB_CLK_MDIV_CH0 "cpu_mdiv_ch0"
> +#define BRCMSTB_CLK_NDIV_INT "cpu_ndiv_int"
> +#define BRCMSTB_CLK_SW_SCB "sw_scb"
> +
> +#define BRCMSTB_TBL_SAFE_MODE BIT(0)
> +#define BRCMSTB_REG_SAFE_MODE BIT(4)
> +
> +/* This is as low as we'll go in the frequency table. */
> +#define MIN_CPU_FREQ (100 * 1000) /* in kHz */
> +
> +struct private_data {
> + void __iomem *cpu_clk_ctrl_reg;
> + struct device *dev;
> +};
> +
> +/* Count the active memory controllers in the system. */
> +static int count_memory_controllers(void)
> +{
> + struct device_node *np = NULL;
> + int i = 0;
> +
> + do {
> + np = of_find_compatible_node(np, NULL, BRCMSTB_DT_MEMC_DDR);
> + if (of_device_is_available(np))
> + i++;
> + of_node_put(np);
> + } while (np);
> +
> + return i;
> +}
> +
> +static int get_frequencies(const struct cpufreq_policy *policy,
> + unsigned int *vco_freq, unsigned int *cpu_freq,
> + unsigned int *scb_freq)
> +{
> + struct clk *cpu_ndiv_int, *sw_scb;
> +
> + cpu_ndiv_int = __clk_lookup(BRCMSTB_CLK_NDIV_INT);
> + if (!cpu_ndiv_int)
> + return -ENODEV;
> +
> + sw_scb = __clk_lookup(BRCMSTB_CLK_SW_SCB);
> + if (!sw_scb)
> + return -ENODEV;
> +
> + /* return frequencies in kHz */
> + *vco_freq = clk_get_rate(cpu_ndiv_int) / 1000;
> + *cpu_freq = clk_get_rate(policy->clk) / 1000;
> + *scb_freq = clk_get_rate(sw_scb) / 1000;
> +
> + return 0;
> +}
> +
> +/*
> + * Safe mode: When set, the CPU's bus unit is being throttled. This is done
> to
> + * avoid buffer overflows when the CPU-to-bus-clock ratio is low.
> + *
> + * The formula as to what constitutes a low CPU-to-bus-clock ratio takes into
> + * account the number of memory controllers active in the system and the SCB
> + * frequency. More memory controllers means safe mode is required starting at
> + * higher frequencies.
> + *
> + * For 1 memory controller, cpu_freq/scb_freq must be greater than or equal
> to
> + * 2 to not require safe mode.
> + *
> + * For 2 or 3 memory controllers, cpu_freq/scb_freq must be greater than or
> + * equal 3 to not require safe mode.
> + */
> +
> +static int freq_requires_safe_mode(unsigned int cpu_freq, unsigned int
> scb_freq,
> + int num_memc)
> +{
> + unsigned int safe_ratio;
> +
> + switch (num_memc) {
> + case 1:
> + safe_ratio = 2;
> + break;
> + case 2:
> + case 3:
> + safe_ratio = 3;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return ((cpu_freq / scb_freq) < safe_ratio);
> +}
> +
> +static struct cpufreq_frequency_table *
> +brcmstb_get_freq_table(const struct cpufreq_policy *policy)
> +{
> + unsigned int cpu_freq, vco_freq, scb_freq, mdiv, init_mdiv, f;
> + struct cpufreq_frequency_table *table;
> + struct private_data *priv;
> + int num_memc, ret;
> + unsigned int i = 0;
> +
> + ret = get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + priv = policy->driver_data;
> + num_memc = count_memory_controllers();
> +
> + /* Calculate the initial mdiv value. We'll increment mdiv from here. */
> + init_mdiv = vco_freq / cpu_freq;
> +
> + /* Count how many frequencies we'll offer. */
> + f = cpu_freq;
> + for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
> + /* We only want to use "whole" MHz. */
> + if ((f % 1000) == 0)
> + i++;
> + }
> +
> + table = devm_kzalloc(priv->dev, (i + 1) * sizeof(*table), GFP_KERNEL);
> + if (!table)
> + return ERR_PTR(-ENOMEM);
> +
> + /* Now, fill the table. */
> + f = cpu_freq;
> + i = 0;
> + for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
> + if ((f % 1000) == 0) {
> + table[i].frequency = f;
> + ret = freq_requires_safe_mode(f, scb_freq, num_memc);
> + if (ret < 0)
> + return ERR_PTR(ret);
> + if (ret > 0)
> + table[i].driver_data |= BRCMSTB_TBL_SAFE_MODE;
> + i++;
> + }
> + }
> + table[i].frequency = CPUFREQ_TABLE_END;
> +
> + return table;
> +}
> +
> +static unsigned int brcmstb_cpufreq_get(unsigned int cpu)
> +{
> + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> +
> + return clk_get_rate(policy->clk) / 1000;
> +}
Rather use cpufreq_generic_get().
> +
> +static int brcmstb_target_index(struct cpufreq_policy *policy,
> + unsigned int index)
> +{
> + struct cpufreq_frequency_table *entry;
> + struct private_data *priv;
> + int ret, safe_mode_needed;
> + u32 reg;
> +
> + priv = policy->driver_data;
> + entry = &policy->freq_table[index];
> + safe_mode_needed = entry->driver_data & BRCMSTB_TBL_SAFE_MODE;
> +
> + reg = readl(priv->cpu_clk_ctrl_reg);
> + if (safe_mode_needed && !(reg & BRCMSTB_REG_SAFE_MODE)) {
> + reg |= BRCMSTB_REG_SAFE_MODE;
> + writel(reg, priv->cpu_clk_ctrl_reg);
> + }
> + ret = clk_set_rate(policy->clk, entry->frequency * 1000);
> + if (!ret && !safe_mode_needed && (reg & BRCMSTB_REG_SAFE_MODE)) {
> + reg &= ~BRCMSTB_REG_SAFE_MODE;
> + writel(reg, priv->cpu_clk_ctrl_reg);
> + }
> +
> + return ret;
> +}
> +
> +/*
> + * All initialization code that we only want to execute once goes here. Setup
> + * code that can be re-tried on every core (if it failed before) can go into
> + * brcm_avs_cpufreq_init().
> + */
> +static int brcmstb_prepare_init(struct platform_device *pdev)
> +{
> + struct private_data *priv;
> + struct resource *res;
> + struct device *dev;
> +
> + /*
> + * If the BRCM STB AVS CPUfreq driver is supported, we bail, so that
> + * the more modern approach implementing DVFS in firmware can be used.
> + */
> + if (IS_ENABLED(CONFIG_ARM_BRCM_AVS_CPUFREQ)) {
> + struct device_node *np;
> +
> + np = of_find_compatible_node(NULL, NULL, BRCM_AVS_CPU_DATA);
> + if (np) {
> + of_node_put(np);
> + return -ENXIO;
> + }
> + }
> +
> + dev = &pdev->dev;
> +
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + priv->cpu_clk_ctrl_reg = devm_ioremap_resource(dev, res);
> + if (IS_ERR(priv->cpu_clk_ctrl_reg)) {
> + dev_err(dev, "couldn't map DT entry %s\n",
> + BRCMSTB_DT_CPU_CLK_CTRL);
> + return -ENODEV;
> + }
> +
> + priv->dev = dev;
> + platform_set_drvdata(pdev, priv);
> +
> + return 0;
> +}
> +
> +static int brcmstb_cpu_init(struct cpufreq_policy *policy)
> +{
> + struct cpufreq_frequency_table *freq_table;
> + struct platform_device *pdev;
> + struct private_data *priv;
> + struct clk *cpu_mdiv_ch0;
> + struct device *dev;
> + int ret;
> +
> + cpu_mdiv_ch0 = __clk_lookup(BRCMSTB_CLK_MDIV_CH0);
> + if (!cpu_mdiv_ch0)
> + return -ENODEV;
> +
> + pdev = cpufreq_get_driver_data();
> + priv = platform_get_drvdata(pdev);
> + dev = &pdev->dev;
> +
> + policy->clk = cpu_mdiv_ch0;
> + policy->driver_data = priv;
> +
> + freq_table = brcmstb_get_freq_table(policy);
> + if (IS_ERR(freq_table)) {
> + ret = PTR_ERR(freq_table);
> + dev_err(dev, "Couldn't determine frequency table (%d).\n", ret);
> + if (ret == -EINVAL)
> + dev_emerg(dev,
> + "Invalid number of memory controllers -- %d!\n",
> + count_memory_controllers());
> + return ret;
> + }
> +
> + ret = cpufreq_table_validate_and_show(policy, freq_table);
> + if (ret) {
> + dev_err(dev, "invalid frequency table: %d\n", ret);
> + return ret;
> + }
> +
> + dev_info(dev, "registered\n");
> +
> + /* All cores share the same clock and thus the same policy. */
> + cpumask_setall(policy->cpus);
You can use cpufreq_generic_init() instead of above two calls.
> +
> + /* We start at the first entry in the frequency table. */
> + policy->cur = freq_table[0].frequency;
No, you can't update policy->cur by yourself. Its for the core to
handle it. Though check if you want to use
CPUFREQ_NEED_INITIAL_FREQ_CHECK.
> +
> + return 0;
> +}
> +
> +/* Shows the number of memory controllers. */
> +static ssize_t show_brcmstb_num_memc(struct cpufreq_policy *policy, char
> *buf)
> +{
> + return sprintf(buf, "%u\n", count_memory_controllers());
> +}
> +
> +/* Shows vco_freq, cpu_freq, and scb_freq in kHz. */
> +static ssize_t show_brcmstb_freqs(struct cpufreq_policy *policy, char *buf)
> +{
> + unsigned int vco_freq, cpu_freq, scb_freq;
> + int ret;
> +
> + ret = get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
> + if (ret)
> + return sprintf(buf, "<unknown>\n");
> +
> + return sprintf(buf, "%u %u %u\n", vco_freq, cpu_freq, scb_freq);
> +}
> +
> +/* Shows the lowest frequency (in kHz) that can be used without "safe mode".
> */
> +static ssize_t show_brcmstb_safe_freq(struct cpufreq_policy *policy, char
> *buf)
> +{
> + unsigned int vco_freq, cpu_freq, scb_freq;
> + unsigned int safe_freq = 0;
> + int i, num_memc, ret;
> +
> + ret = get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
> + if (ret)
> + return sprintf(buf, "<unknown>\n");
> +
> + num_memc = count_memory_controllers();
> +
> + for (i = 0; policy->freq_table[i].frequency != CPUFREQ_TABLE_END; i++) {
You can use cpufreq_for_each_valid_entry() here.
> + ret = freq_requires_safe_mode(policy->freq_table[i].frequency,
> + scb_freq, num_memc);
> + if (ret < 0)
> + return sprintf(buf, "<error> (%d)\n", ret);
> + if (ret == 0)
> + safe_freq = policy->freq_table[i].frequency;
You don't want to break from the loop here ?
> + }
> +
> + return sprintf(buf, "%u\n", safe_freq);
> +}
> +
> +cpufreq_freq_attr_ro(brcmstb_num_memc);
> +cpufreq_freq_attr_ro(brcmstb_freqs);
> +cpufreq_freq_attr_ro(brcmstb_safe_freq);
> +
> +static struct freq_attr *brcmstb_cpufreq_attr[] = {
> + &cpufreq_freq_attr_scaling_available_freqs,
> + &brcmstb_num_memc,
> + &brcmstb_freqs,
> + &brcmstb_safe_freq,
> + NULL
> +};
> +
> +static struct cpufreq_driver brcmstb_driver = {
> + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
> + .verify = cpufreq_generic_frequency_table_verify,
> + .target_index = brcmstb_target_index,
> + .get = brcmstb_cpufreq_get,
> + .init = brcmstb_cpu_init,
What about .exit ?
> + .attr = brcmstb_cpufreq_attr,
> + .name = BRCMSTB_CPUFREQ_PREFIX,
> +};
> +
> +static int brcmstb_cpufreq_probe(struct platform_device *pdev)
> +{
> + int ret;
> +
> + ret = brcmstb_prepare_init(pdev);
> + if (ret)
> + return ret;
> +
> + brcmstb_driver.driver_data = pdev;
> +
> + return cpufreq_register_driver(&brcmstb_driver);
> +}
> +
> +static int brcmstb_cpufreq_remove(struct platform_device *pdev)
> +{
> + int ret;
> +
> + ret = cpufreq_unregister_driver(&brcmstb_driver);
> + if (ret)
> + return ret;
> +
> + platform_set_drvdata(pdev, NULL);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id brcmstb_cpufreq_match[] = {
> + { .compatible = BRCMSTB_DT_CPU_CLK_CTRL },
> + { }
> +};
> +MODULE_DEVICE_TABLE(platform, brcmstb_cpufreq_match);
> +
> +static struct platform_driver brcmstb_cpufreq_platdrv = {
How is the device getting created for this? Be aware the DT can't have
a separate node for cpufreq-device ..
> + .driver = {
> + .name = BRCMSTB_CPUFREQ_NAME,
> + .of_match_table = brcmstb_cpufreq_match,
> + },
> + .probe = brcmstb_cpufreq_probe,
> + .remove = brcmstb_cpufreq_remove,
> +};
> +module_platform_driver(brcmstb_cpufreq_platdrv);
> +
> +MODULE_AUTHOR("Markus Mayer <mma...@broadcom.com>");
> +MODULE_DESCRIPTION("CPUfreq driver for Broadcom STB SoCs");
> +MODULE_LICENSE("GPL");
--
viresh
