--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * CPU frequency scaling support for Armada 37xx platform.
+ *
+ * Copyright (C) 2017 Marvell
+ *
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* Power management in North Bridge register set */
+#define ARMADA_37XX_NB_L0L1 0x18
+#define ARMADA_37XX_NB_L2L3 0x1C
+#define ARMADA_37XX_NB_TBG_DIV_OFF 13
+#define ARMADA_37XX_NB_TBG_DIV_MASK 0x7
+#define ARMADA_37XX_NB_CLK_SEL_OFF 11
+#define ARMADA_37XX_NB_CLK_SEL_MASK 0x1
+#define ARMADA_37XX_NB_CLK_SEL_TBG 0x1
+#define ARMADA_37XX_NB_TBG_SEL_OFF 9
+#define ARMADA_37XX_NB_TBG_SEL_MASK 0x3
+#define ARMADA_37XX_NB_VDD_SEL_OFF 6
+#define ARMADA_37XX_NB_VDD_SEL_MASK 0x3
+#define ARMADA_37XX_NB_CONFIG_SHIFT 16
+#define ARMADA_37XX_NB_DYN_MOD 0x24
+#define ARMADA_37XX_NB_CLK_SEL_EN BIT(26)
+#define ARMADA_37XX_NB_TBG_EN BIT(28)
+#define ARMADA_37XX_NB_DIV_EN BIT(29)
+#define ARMADA_37XX_NB_VDD_EN BIT(30)
+#define ARMADA_37XX_NB_DFS_EN BIT(31)
+#define ARMADA_37XX_NB_CPU_LOAD 0x30
+#define ARMADA_37XX_NB_CPU_LOAD_MASK 0x3
+#define ARMADA_37XX_DVFS_LOAD_0 0
+#define ARMADA_37XX_DVFS_LOAD_1 1
+#define ARMADA_37XX_DVFS_LOAD_2 2
+#define ARMADA_37XX_DVFS_LOAD_3 3
+
+/*
+ * On Armada 37xx the Power management manages 4 level of CPU load,
+ * each level can be associated with a CPU clock source, a CPU
+ * divider, a VDD level, etc...
+ */
+#define LOAD_LEVEL_NR 4
+
+struct armada_37xx_dvfs {
+ u32 cpu_freq_max;
+ u8 divider[LOAD_LEVEL_NR];
+};
+
+static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
+ {.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} },
+ {.cpu_freq_max = 1000*1000*1000, .divider = {1, 2, 4, 5} },
+ {.cpu_freq_max = 800*1000*1000, .divider = {1, 2, 3, 4} },
+ {.cpu_freq_max = 600*1000*1000, .divider = {2, 4, 5, 6} },
+};
+
+static struct armada_37xx_dvfs *armada_37xx_cpu_freq_info_get(u32 freq)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(armada_37xx_dvfs); i++) {
+ if (freq == armada_37xx_dvfs[i].cpu_freq_max)
+ return &armada_37xx_dvfs[i];
+ }
+
+ pr_err("Unsupported CPU frequency %d MHz\n", freq/1000000);
+ return NULL;
+}
+
+/*
+ * Setup the four level managed by the hardware. Once the four level
+ * will be configured then the DVFS will be enabled.
+ */
+static void __init armada37xx_cpufreq_dvfs_setup(struct regmap *base,
+ struct clk *clk, u8 *divider)
+{
+ int load_lvl;
+ struct clk *parent;
+
+ for (load_lvl = 0; load_lvl < LOAD_LEVEL_NR; load_lvl++) {
+ unsigned int reg, mask, val, offset = 0;
+
+ if (load_lvl <= ARMADA_37XX_DVFS_LOAD_1)
+ reg = ARMADA_37XX_NB_L0L1;
+ else
+ reg = ARMADA_37XX_NB_L2L3;
+
+ if (load_lvl == ARMADA_37XX_DVFS_LOAD_0 ||
+ load_lvl == ARMADA_37XX_DVFS_LOAD_2)
+ offset += ARMADA_37XX_NB_CONFIG_SHIFT;
+
+ /* Set cpu clock source, for all the level we use TBG */
+ val = ARMADA_37XX_NB_CLK_SEL_TBG << ARMADA_37XX_NB_CLK_SEL_OFF;
+ mask = (ARMADA_37XX_NB_CLK_SEL_MASK
+ << ARMADA_37XX_NB_CLK_SEL_OFF);
+
+ /*
+ * Set cpu divider based on the pre-computed array in
+ * order to have balanced step.
+ */
+ val |= divider[load_lvl] << ARMADA_37XX_NB_TBG_DIV_OFF;
+ mask |= (ARMADA_37XX_NB_TBG_DIV_MASK
+ << ARMADA_37XX_NB_TBG_DIV_OFF);
+
+ /* Set VDD divider which is actually the load level. */
+ val |= load_lvl << ARMADA_37XX_NB_VDD_SEL_OFF;
+ mask |= (ARMADA_37XX_NB_VDD_SEL_MASK
+ << ARMADA_37XX_NB_VDD_SEL_OFF);
+
+ val <<= offset;
+ mask <<= offset;
+
+ regmap_update_bits(base, reg, mask, val);
+ }
+
+ /*
+ * Set cpu clock source, for all the level we keep the same
+ * clock source that the one already configured. For this one
+ * we need to use the clock framework
+ */
+ parent = clk_get_parent(clk);
+ clk_set_parent(clk, parent);
+}
+
+static void __init armada37xx_cpufreq_disable_dvfs(struct regmap *base)
+{
+ unsigned int reg = ARMADA_37XX_NB_DYN_MOD,
+ mask = ARMADA_37XX_NB_DFS_EN;
+
+ regmap_update_bits(base, reg, mask, 0);
+}
+
+static void __init armada37xx_cpufreq_enable_dvfs(struct regmap *base)
+{
+ unsigned int val, reg = ARMADA_37XX_NB_CPU_LOAD,
+ mask = ARMADA_37XX_NB_CPU_LOAD_MASK;
+
+ /* Start with the highest load (0) */
+ val = ARMADA_37XX_DVFS_LOAD_0;
+ regmap_update_bits(base, reg, mask, val);
+
+ /* Now enable DVFS for the CPUs */
+ reg = ARMADA_37XX_NB_DYN_MOD;
+ mask = ARMADA_37XX_NB_CLK_SEL_EN | ARMADA_37XX_NB_TBG_EN |
+ ARMADA_37XX_NB_DIV_EN | ARMADA_37XX_NB_VDD_EN |
+ ARMADA_37XX_NB_DFS_EN;
+
+ regmap_update_bits(base, reg, mask, mask);
+}
+
+static int __init armada37xx_cpufreq_driver_init(void)
+{
+ struct armada_37xx_dvfs *dvfs;
+ struct platform_device *pdev;
+ unsigned int cur_frequency;
+ struct regmap *nb_pm_base;
+ struct device *cpu_dev;
+ int load_lvl, ret;
+ struct clk *clk;
+
+ nb_pm_base =
+ syscon_regmap_lookup_by_compatible("marvell,armada-3700-nb-pm");
+
+ if (IS_ERR(nb_pm_base))
+ return -ENODEV;
+
+ /* Before doing any configuration on the DVFS first, disable it */
+ armada37xx_cpufreq_disable_dvfs(nb_pm_base);
+
+ /*
+ * On CPU 0 register the operating points supported (which are
+ * the nominal CPU frequency and full integer divisions of
+ * it).
+ */
+ cpu_dev = get_cpu_device(0);
+ if (!cpu_dev) {
+ dev_err(cpu_dev, "Cannot get CPU\n");
+ return -ENODEV;
+ }
+
+ clk = clk_get(cpu_dev, 0);
+ if (IS_ERR(clk)) {
+ dev_err(cpu_dev, "Cannot get clock for CPU0\n");
+ return PTR_ERR(clk);
+ }
+
+ /* Get nominal (current) CPU frequency */
+ cur_frequency = clk_get_rate(clk);
+ if (!cur_frequency) {
+ dev_err(cpu_dev, "Failed to get clock rate for CPU\n");
+ return -EINVAL;
+ }
+
+ dvfs = armada_37xx_cpu_freq_info_get(cur_frequency);
+ if (!dvfs)
+ return -EINVAL;
+
+ armada37xx_cpufreq_dvfs_setup(nb_pm_base, clk, dvfs->divider);
+
+ for (load_lvl = ARMADA_37XX_DVFS_LOAD_0; load_lvl < LOAD_LEVEL_NR;
+ load_lvl++) {
+ unsigned long freq = cur_frequency / dvfs->divider[load_lvl];
+
+ ret = dev_pm_opp_add(cpu_dev, freq, 0);
+ if (ret) {
+ /* clean-up the already added opp before leaving */
+ while (load_lvl-- > ARMADA_37XX_DVFS_LOAD_0) {
+ freq = cur_frequency / dvfs->divider[load_lvl];
+ dev_pm_opp_remove(cpu_dev, freq);
+ }
+ return ret;
+ }
+ }
+
+ /* Now that everything is setup, enable the DVFS at hardware level */
+ armada37xx_cpufreq_enable_dvfs(nb_pm_base);
+
+ pdev = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
+
+ return PTR_ERR_OR_ZERO(pdev);
+}
+/* late_initcall, to guarantee the driver is loaded after A37xx clock driver */
+late_initcall(armada37xx_cpufreq_driver_init);
+
+MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@free-electrons.com>");
+MODULE_DESCRIPTION("Armada 37xx cpufreq driver");
+MODULE_LICENSE("GPL");
projects / linux.git / commitdiff