1 files changed, 241 insertions, 0 deletions
diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
new file mode 100644
index 000000000000..c6ebc88a7d8d
--- /dev/null
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -0,0 +1,241 @@
+// 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");