[PATCH 3/6] clk: mvebu: add CPU clock driver for Armada 7K/8K

[Gregory CLEMENT <gregory.clement@bootlin.com>]

The CPU frequency is managed at the AP level for the Armada 7K/8K. The
CPU frequency is modified by cluster: the CPUs of the same cluster have
the same frequency.

This patch adds the clock driver that will be used by CPUFreq, it is
based on the work of Omri Itach <omrii@marvell.com>.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
 drivers/clk/mvebu/Kconfig      |   3 +
 drivers/clk/mvebu/Makefile     |   1 +
 drivers/clk/mvebu/ap-cpu-clk.c | 265 +++++++++++++++++++++++++++++++++
 3 files changed, 269 insertions(+)
 create mode 100644 drivers/clk/mvebu/ap-cpu-clk.c

diff --git a/drivers/clk/mvebu/Kconfig b/drivers/clk/mvebu/Kconfig
index 5492fae3f0ab..9d0b2f7cee21 100644
--- a/drivers/clk/mvebu/Kconfig
+++ b/drivers/clk/mvebu/Kconfig
@@ -39,6 +39,9 @@ config ARMADA_AP806_SYSCON
 	bool
 	select ARMADA_AP_CP_HELPER
 
+config ARMADA_AP_CPU_CLK
+	bool
+
 config ARMADA_CP110_SYSCON
 	bool
 	select ARMADA_AP_CP_HELPER
diff --git a/drivers/clk/mvebu/Makefile b/drivers/clk/mvebu/Makefile
index 6638ad962ec1..04464cef0f06 100644
--- a/drivers/clk/mvebu/Makefile
+++ b/drivers/clk/mvebu/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_ARMADA_37XX_CLK)	+= armada-37xx-tbg.o
 obj-$(CONFIG_ARMADA_37XX_CLK)	+= armada-37xx-periph.o
 obj-$(CONFIG_ARMADA_XP_CLK)	+= armada-xp.o mv98dx3236.o
 obj-$(CONFIG_ARMADA_AP806_SYSCON) += ap806-system-controller.o
+obj-$(CONFIG_ARMADA_AP_CPU_CLK) += ap-cpu-clk.o
 obj-$(CONFIG_ARMADA_CP110_SYSCON) += cp110-system-controller.o
 obj-$(CONFIG_DOVE_CLK)		+= dove.o dove-divider.o
 obj-$(CONFIG_KIRKWOOD_CLK)	+= kirkwood.o
diff --git a/drivers/clk/mvebu/ap-cpu-clk.c b/drivers/clk/mvebu/ap-cpu-clk.c
new file mode 100644
index 000000000000..1b498cfe9191
--- /dev/null
+++ b/drivers/clk/mvebu/ap-cpu-clk.c
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Marvell Armada AP CPU Clock Controller
+ *
+ * Copyright (C) 2018 Marvell
+ *
+ * Omri Itach <omrii@marvell.com>
+ * Gregory Clement <gregory.clement@bootlin.com>
+ */
+
+#define pr_fmt(fmt) "ap-cpu-clk: " fmt
+
+#include "armada_ap_cp_helper.h"
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/init.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define AP806_CPU_CLUSTER0		0
+#define AP806_CPU_CLUSTER1		1
+#define AP806_CPUS_PER_CLUSTER		2
+#define APN806_CPU1_MASK		0x1
+
+#define APN806_CLUSTER_NUM_OFFSET	8
+#define APN806_CLUSTER_NUM_MASK		(1 << APN806_CLUSTER_NUM_OFFSET)
+
+#define APN806_MAX_DIVIDER		32
+
+/* AP806 CPU DFS register mapping*/
+#define AP806_CA72MP2_0_PLL_CR_0_REG_OFFSET		0x278
+#define AP806_CA72MP2_0_PLL_CR_1_REG_OFFSET		0x280
+#define AP806_CA72MP2_0_PLL_CR_2_REG_OFFSET		0x284
+#define AP806_CA72MP2_0_PLL_SR_REG_OFFSET		0xC94
+
+#define AP806_CA72MP2_0_PLL_CR_CLUSTER_OFFSET		0x14
+#define AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_OFFSET		0
+#define AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_MASK \
+			(0x3f << AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_OFFSET)
+#define AP806_PLL_CR_0_CPU_CLK_RELOAD_FORCE_OFFSET	24
+#define AP806_PLL_CR_0_CPU_CLK_RELOAD_FORCE_MASK \
+			(0x1 << AP806_PLL_CR_0_CPU_CLK_RELOAD_FORCE_OFFSET)
+#define AP806_PLL_CR_0_CPU_CLK_RELOAD_RATIO_OFFSET	16
+#define AP806_CA72MP2_0_PLL_RATIO_STATE			11
+
+#define to_clk(hw) container_of(hw, struct ap_cpu_clk, hw)
+
+/*
+ * struct ap806_clk: CPU cluster clock controller instance
+ * @cluster: Cluster clock controller index
+ * @clk_name: Cluster clock controller name
+ * @dev : Cluster clock device
+ * @hw: HW specific structure of Cluster clock controller
+ * @pll_cr_base: CA72MP2 Register base (Device Sample at Reset register)
+ */
+struct ap_cpu_clk {
+	int cluster;
+	const char *clk_name;
+	struct device *dev;
+	struct clk_hw hw;
+	struct regmap *pll_cr_base;
+};
+
+static struct clk **cluster_clks;
+static struct clk_onecell_data clk_data;
+
+static unsigned long ap_cpu_clk_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	struct ap_cpu_clk *clk = to_clk(hw);
+	unsigned int cpu_clkdiv_reg = AP806_CA72MP2_0_PLL_CR_0_REG_OFFSET +
+		(clk->cluster * AP806_CA72MP2_0_PLL_CR_CLUSTER_OFFSET);
+	int cpu_clkdiv_ratio;
+
+	regmap_read(clk->pll_cr_base, cpu_clkdiv_reg, &cpu_clkdiv_ratio);
+	cpu_clkdiv_ratio &= AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_MASK;
+	cpu_clkdiv_ratio >>= AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_OFFSET;
+
+	return parent_rate / cpu_clkdiv_ratio;
+}
+
+static int ap_cpu_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long parent_rate)
+{
+	struct ap_cpu_clk *clk = to_clk(hw);
+	int reg, divider = parent_rate / rate;
+	unsigned int cpu_clkdiv_reg, cpu_force_reg, cpu_ratio_reg;
+
+	cpu_clkdiv_reg = AP806_CA72MP2_0_PLL_CR_0_REG_OFFSET +
+		(clk->cluster * AP806_CA72MP2_0_PLL_CR_CLUSTER_OFFSET);
+	cpu_force_reg = AP806_CA72MP2_0_PLL_CR_1_REG_OFFSET +
+		(clk->cluster * AP806_CA72MP2_0_PLL_CR_CLUSTER_OFFSET);
+	cpu_ratio_reg = AP806_CA72MP2_0_PLL_CR_2_REG_OFFSET +
+		(clk->cluster * AP806_CA72MP2_0_PLL_CR_CLUSTER_OFFSET);
+
+	/* 1. Set CPU divider */
+	regmap_update_bits(clk->pll_cr_base, cpu_clkdiv_reg,
+			   AP806_PLL_CR_0_CPU_CLK_DIV_RATIO_MASK, divider);
+
+	/* 2. Set Reload force */
+	regmap_update_bits(clk->pll_cr_base, cpu_force_reg,
+			   AP806_PLL_CR_0_CPU_CLK_RELOAD_FORCE_MASK,
+			   AP806_PLL_CR_0_CPU_CLK_RELOAD_FORCE_MASK);
+
+	/* 3. Set Reload ratio */
+	regmap_update_bits(clk->pll_cr_base, cpu_ratio_reg,
+			   BIT(AP806_PLL_CR_0_CPU_CLK_RELOAD_RATIO_OFFSET),
+			   BIT(AP806_PLL_CR_0_CPU_CLK_RELOAD_RATIO_OFFSET));
+
+
+	/* 4. Wait for stabilizing CPU Clock */
+	do {
+		regmap_read(clk->pll_cr_base,
+			    AP806_CA72MP2_0_PLL_SR_REG_OFFSET,
+			    &reg);
+	} while (!(reg & BIT(clk->cluster * AP806_CA72MP2_0_PLL_RATIO_STATE)));
+
+	/* 5. Clear Reload ratio */
+	regmap_update_bits(clk->pll_cr_base, cpu_ratio_reg,
+			   BIT(AP806_PLL_CR_0_CPU_CLK_RELOAD_RATIO_OFFSET), 0);
+
+	return 0;
+}
+
+
+static long ap_cpu_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long *parent_rate)
+{
+	int divider = *parent_rate / rate;
+
+	if (divider > APN806_MAX_DIVIDER)
+		divider = APN806_MAX_DIVIDER;
+
+	return *parent_rate / divider;
+}
+
+static const struct clk_ops ap_cpu_clk_ops = {
+	.recalc_rate	= ap_cpu_clk_recalc_rate,
+	.round_rate	= ap_cpu_clk_round_rate,
+	.set_rate	= ap_cpu_clk_set_rate,
+};
+
+static int ap_cpu_clock_probe(struct platform_device *pdev)
+{
+	int ret, nclusters = 0, cluster_index = 0;
+	struct device *dev = &pdev->dev;
+	struct device_node *dn, *np = dev->of_node;
+	struct ap_cpu_clk *ap_cpu_clk;
+	struct regmap *regmap;
+
+	regmap = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(regmap)) {
+		pr_err("cannot get pll_cr_base regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	/*
+	 * AP806 has 4 cpus and DFS for AP806 is controlled per
+	 * cluster (2 CPUs per cluster), cpu0 and cpu1 are fixed to
+	 * cluster0 while cpu2 and cpu3 are fixed to cluster1 whether
+	 * they are enabled or not.  Since cpu0 is the boot cpu, then
+	 * cluster0 must exist.  If cpu2 or cpu3 is enabled, cluster1
+	 * will exist and the cluster number is 2; otherwise the
+	 * cluster number is 1.
+	 */
+	nclusters = 1;
+	for_each_node_by_type(dn, "cpu") {
+		int cpu, err;
+
+		err = of_property_read_u32(dn, "reg", &cpu);
+		if (WARN_ON(err))
+			return err;
+
+		/* If cpu2 or cpu3 is enabled */
+		if ((cpu & APN806_CLUSTER_NUM_MASK)) {
+			nclusters = 2;
+			break;
+		}
+	}
+	/*
+	 * DFS for AP806 is controlled per cluster (2 CPUs per cluster),
+	 * so allocate structs per cluster
+	 */
+	ap_cpu_clk = devm_kcalloc(dev, nclusters, sizeof(*ap_cpu_clk),
+				  GFP_KERNEL);
+	if (WARN_ON(!ap_cpu_clk))
+		return -ENOMEM;
+
+	cluster_clks = devm_kcalloc(dev, nclusters, sizeof(*cluster_clks),
+				    GFP_KERNEL);
+	if (WARN_ON(!cluster_clks))
+		return -ENOMEM;
+
+	for_each_node_by_type(dn, "cpu") {
+		char *clk_name = "cpu-cluster-0";
+		struct clk_init_data init;
+		const char *parent_name;
+		struct clk *clk, *parent;
+		int cpu, err;
+
+		err = of_property_read_u32(dn, "reg", &cpu);
+		if (WARN_ON(err))
+			return err;
+
+		cluster_index = (cpu & APN806_CLUSTER_NUM_MASK);
+		cluster_index >>= APN806_CLUSTER_NUM_OFFSET;
+
+		/* Initialize once for one cluster */
+		if (cluster_clks[cluster_index])
+			continue;
+
+		parent = of_clk_get(np, cluster_index);
+		if (IS_ERR(parent)) {
+			dev_err(dev, "Could not get the clock parent\n");
+			return -EINVAL;
+		}
+		parent_name =  __clk_get_name(parent);
+		clk_name[12] += cluster_index;
+		ap_cpu_clk[cluster_index].clk_name =
+			ap_cp_unique_name(dev, np->parent, clk_name);
+		ap_cpu_clk[cluster_index].cluster = cluster_index;
+		ap_cpu_clk[cluster_index].pll_cr_base = regmap;
+		ap_cpu_clk[cluster_index].hw.init = &init;
+		ap_cpu_clk[cluster_index].dev = dev;
+
+		init.name = ap_cpu_clk[cluster_index].clk_name;
+		init.ops = &ap_cpu_clk_ops;
+		init.num_parents = 1;
+		init.parent_names = &parent_name;
+		init.flags = CLK_GET_RATE_NOCACHE;
+
+		clk = devm_clk_register(dev, &ap_cpu_clk[cluster_index].hw);
+		if (IS_ERR(clk))
+			return PTR_ERR(clk);
+
+		cluster_clks[cluster_index] = clk;
+	}
+
+	clk_data.clk_num = cluster_index + 1;
+	clk_data.clks = cluster_clks;
+
+	ret = of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+	if (ret)
+		dev_err(dev, "failed to register OF clock provider\n");
+
+	return ret;
+}
+
+static const struct of_device_id ap_cpu_clock_of_match[] = {
+	{ .compatible = "marvell,ap806-cpu-clock", },
+	{ }
+};
+
+static struct platform_driver ap_cpu_clock_driver = {
+	.probe = ap_cpu_clock_probe,
+	.driver		= {
+		.name	= "marvell-ap-cpu-clock",
+		.of_match_table = ap_cpu_clock_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(ap_cpu_clock_driver);
-- 
2.19.0