[PATCH v5 2/7] clk: samsung: add infrastructure to register cpu clocks

From: Thomas Abraham <[email protected]>

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.

Cc: Tomasz Figa <[email protected]>
Signed-off-by: Thomas Abraham <[email protected]>
---
 drivers/clk/samsung/Makefile  |    2 +-
 drivers/clk/samsung/clk-cpu.c |  448 +++++++++++++++++++++++++++++++++++++++++
 drivers/clk/samsung/clk.h     |    4 +
 3 files changed, 453 insertions(+), 1 deletion(-)
 create mode 100644 drivers/clk/samsung/clk-cpu.c

diff --git a/drivers/clk/samsung/Makefile b/drivers/clk/samsung/Makefile
index 25646c6..83620a1 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-$(CONFIG_SOC_EXYNOS3250)	+= clk-exynos3250.o
 obj-$(CONFIG_ARCH_EXYNOS4)	+= clk-exynos4.o
 obj-$(CONFIG_SOC_EXYNOS5250)	+= clk-exynos5250.o
diff --git a/drivers/clk/samsung/clk-cpu.c b/drivers/clk/samsung/clk-cpu.c
new file mode 100644
index 0000000..13fa4c5
--- /dev/null
+++ b/drivers/clk/samsung/clk-cpu.c
@@ -0,0 +1,448 @@
+/*
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Thomas Abraham <[email protected]>
+ *
+ * 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
+
+#define DIV_CPU0_RATIO0_MASK	0x7
+
+#define MAX_DIV			8
+
+#define EXYNOS4210_ARM_DIV1(div) ((div & 0x7) + 1)
+#define EXYNOS4210_ARM_DIV2(div) (((div >> 28) & 0x7) + 1)
+
+#define EXYNOS4210_DIV_CPU0(d5, d4, d3, d2, d1, d0)			\
+		(((d5) << 24) | ((d4) << 20) | ((d3) << 16) | ((d2) << 12) | \
+		 ((d1) << 8) | ((d0) <<  4))
+#define EXYNOS4210_DIV_CPU1(d2, d1, d0)					\
+		(((d2) << 8) | ((d1) << 4) | ((d0) << 0))
+
+#define EXYNOS4210_DIV1_HPM_MASK	((0x7 << 0) | (0x7 << 4))
+#define EXYNOS4210_MUX_HPM_MASK		(1 << 20)
+
+/**
+ * struct exynos4210_armclk_data: config data to setup exynos4210 cpu clocks.
+ * @prate:	frequency of the parent clock.
+ * @div0:	value to be programmed in the div_cpu0 register.
+ * @div1:	value to be programmed in the div_cpu1 register.
+ *
+ * This structure holds the divider configuration data for divider clocks
+ * belonging to the CMU_CPU clock domain. The parent frequency at which these
+ * divider values are valid is specified in @prate.
+ */
+struct exynos4210_armclk_data {
+	unsigned long	prate;
+	unsigned int	div0;
+	unsigned int	div1;
+};
+
+/**
+ * struct exynos_cpuclk: information about clock supplied to a CPU core.
+ * @hw:		handle between CCF and CPU clock.
+ * @alt_parent:	alternate parent clock to use when switching the speed
+ *		of the primary parent 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.
+ * @clk_nb:	clock notifier registered for changes in clock speed of the
+ *		primary parent clock.
+ * @lock:	register access lock.
+ * @data:	optional data which the actual instantiation of this clock
+ *		can use.
+ */
+struct exynos_cpuclk {
+	struct clk_hw		hw;
+	struct clk		*alt_parent;
+	void __iomem		*ctrl_base;
+	unsigned long		offset;
+	struct notifier_block	clk_nb;
+	spinlock_t		*lock;
+	void			*data;
+};
+
+#define to_exynos_cpuclk_hw(hw) container_of(hw, struct exynos_cpuclk, hw)
+#define to_exynos_cpuclk_nb(nb) container_of(nb, struct exynos_cpuclk, clk_nb)
+
+/**
+ * struct exynos_cpuclk_soc_data: soc specific data for cpu clocks.
+ * @parser:	pointer to a function that can parse SoC specific data.
+ * @ops:	clock operations to be used for this clock.
+ * @offset:	optional offset from base of clock controller register base, to
+ *		be used when accessing clock controller registers related to the
+ *		CPU clock.
+ * @clk_cb:	the clock notifier callback to be called for changes in the
+ *		clock rate of the primary parent clock.
+ *
+ * This structure provides SoC specific data for ARM clocks. Based on
+ * the compatible value of the clock controller node, the value of the
+ * fields in this structure can be populated.
+ */
+struct exynos_cpuclk_soc_data {
+	int (*parser)(struct device_node *, void **);
+	const struct clk_ops *ops;
+	unsigned int offset;
+	int (*clk_cb)(struct notifier_block *, unsigned long, void *);
+};
+
+/* common round rate callback useable for all types of CPU clocks */
+static long exynos_cpuclk_round_rate(struct clk_hw *hw,
+			unsigned long drate, unsigned long *prate)
+{
+	struct clk *parent = __clk_get_parent(hw->clk);
+	*prate = __clk_round_rate(parent, drate);
+	return *prate;
+}
+
+/* common recalc rate callback useable for all types of CPU clocks */
+static unsigned long exynos_cpuclk_recalc_rate(struct clk_hw *hw,
+			unsigned long parent_rate)
+{
+	return parent_rate;
+}
+
+/*
+ * Calculates the divider value to be set for deriving drate from prate.
+ * Divider value is actual divider value - 1.
+ */
+static unsigned long _calc_div(unsigned long prate, unsigned long drate)
+{
+	unsigned long div = DIV_ROUND_UP(prate, drate) - 1;
+
+	WARN_ON(div >= MAX_DIV);
+	return div;
+}
+
+/* helper function to register a cpu clock */
+static int __init exynos_cpuclk_register(struct samsung_clk_provider *ctx,
+		unsigned int lookup_id, const char *name, const char *parent,
+		const char *alt_parent, struct device_node *np,
+		const struct exynos_cpuclk_soc_data *soc_data)
+{
+	struct exynos_cpuclk *cpuclk;
+	struct clk_init_data init;
+	struct clk *clk;
+	int ret;
+
+	cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
+	if (!cpuclk) {
+		pr_err("%s: could not allocate memory for %s clock\n",
+					__func__, name);
+		return -ENOMEM;
+	}
+
+	init.name = name;
+	init.flags = CLK_SET_RATE_PARENT;
+	init.parent_names = &parent;
+	init.num_parents = 1;
+
+	cpuclk->hw.init = &init;
+	cpuclk->ctrl_base = ctx->reg_base;
+	cpuclk->lock = &ctx->lock;
+
+	ret = soc_data->parser(np, &cpuclk->data);
+	if (ret) {
+		pr_err("%s: error %d in parsing %s clock data",
+				__func__, ret, name);
+		ret = -EINVAL;
+		goto free_cpuclk;
+	}
+	cpuclk->offset = soc_data->offset;
+	init.ops = soc_data->ops;
+
+	cpuclk->clk_nb.notifier_call = soc_data->clk_cb;
+	if (clk_notifier_register(__clk_lookup(parent), &cpuclk->clk_nb)) {
+		pr_err("%s: failed to register clock notifier for %s\n",
+				__func__, name);
+		goto free_cpuclk_data;
+	}
+
+	cpuclk->alt_parent = __clk_lookup(alt_parent);
+	if (!cpuclk->alt_parent) {
+		pr_err("%s: could not lookup alternate parent %s\n",
+				__func__, alt_parent);
+		ret = -EINVAL;
+		goto unregister_clk_nb;
+	}
+
+	clk = clk_register(NULL, &cpuclk->hw);
+	if (IS_ERR(clk)) {
+		pr_err("%s: could not register cpuclk %s\n", __func__,	name);
+		ret = PTR_ERR(clk);
+		goto unregister_clk_nb;
+	}
+
+	samsung_clk_add_lookup(ctx, clk, lookup_id);
+	return 0;
+
+unregister_clk_nb:
+	clk_notifier_unregister(__clk_lookup(parent), &cpuclk->clk_nb);
+free_cpuclk_data:
+	kfree(cpuclk->data);
+free_cpuclk:
+	kfree(cpuclk);
+	return ret;
+}
+
+static void exynos4210_set_armclk_div(void __iomem *base, unsigned long div)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(10);
+	unsigned long div0;
+
+	WARN_ON(div >= MAX_DIV);
+
+	div0 = readl(base + DIV_CPU0);
+	div0 = (div0 & ~DIV_CPU0_RATIO0_MASK) | div;
+	writel(div0, base + DIV_CPU0);
+	while (time_before(jiffies, timeout))
+		if (!readl(base + DIV_STAT_CPU0))
+			return;
+	pr_err("%s: timeout in divider stablization\n", __func__);
+}
+
+static int exynos4210_armclk_pre_rate_change(struct clk_notifier_data *ndata,
+			struct exynos_cpuclk *armclk, void __iomem *base)
+{
+	struct exynos4210_armclk_data *armclk_data = armclk->data;
+	unsigned long alt_prate = clk_get_rate(armclk->alt_parent);
+	unsigned long alt_div = 0, div0, div1, tdiv0, mux_reg;
+	unsigned long timeout, flags;
+
+	/* find out the divider values to use for clock data */
+	while (armclk_data->prate != ndata->new_rate) {
+		if (armclk_data->prate == 0)
+			return -EINVAL;
+		armclk_data++;
+	}
+
+	/* For the selected PLL clock frequency, get the pre-defined divider
+	 * values. If the clock for sclk_hpm is not sourced from apll, then
+	 * the values for DIV_COPY and DIV_HPM dividers need not be set.
+	 */
+	div0 = armclk_data->div0;
+	div1 = armclk_data->div1;
+	if (readl(base + SRC_CPU) & EXYNOS4210_MUX_HPM_MASK) {
+		div1 = readl(base + DIV_CPU1) & EXYNOS4210_DIV1_HPM_MASK;
+		div1 |= ((armclk_data->div1) & ~EXYNOS4210_DIV1_HPM_MASK);
+	}
+
+	spin_lock_irqsave(armclk->lock, flags);
+
+	/*
+	 * if the new and old parent clock speed is less than the clock speed
+	 * of the alternate parent, then it should be ensured that at no point
+	 * the armclk speed is more than the old_prate until the dividers are
+	 * set.
+	 */
+	tdiv0 = readl(base + DIV_CPU0);
+	if (alt_prate > ndata->old_rate) {
+		alt_div = _calc_div(alt_prate, ndata->old_rate);
+		exynos4210_set_armclk_div(base, alt_div);
+		div0 |= alt_div;
+	}
+
+	/* select sclk_mpll as the alternate parent */
+	mux_reg = readl(base + SRC_CPU);
+	writel(mux_reg | (1 << 16), base + SRC_CPU);
+
+	timeout = jiffies + msecs_to_jiffies(10);
+	while (time_before(jiffies, timeout))
+		if (((readl(base + STAT_CPU) >> 16) & 0x7) == 2)
+			break;
+
+	if (((readl(base + STAT_CPU) >> 16) & 0x7) != 2)
+		pr_err("%s: re-parenting to sclk_mpll failed\n", __func__);
+
+	/* alternate parent is active now. set the dividers */
+	writel(div0, base + DIV_CPU0);
+	timeout = jiffies + msecs_to_jiffies(10);
+	while (time_before(jiffies, timeout))
+		if (!readl(base + DIV_STAT_CPU0))
+			break;
+
+	if (readl(base + DIV_STAT_CPU0))
+		pr_err("%s: timeout in divider0 stablization\n", __func__);
+
+	writel(div1, base + DIV_CPU1);
+	timeout = jiffies + msecs_to_jiffies(10);
+	while (time_before(jiffies, timeout))
+		if (!readl(base + DIV_STAT_CPU1))
+			break;
+	if (readl(base + DIV_STAT_CPU1))
+		pr_err("%s: timeout in divider1 stablization\n", __func__);
+
+	spin_unlock_irqrestore(armclk->lock, flags);
+	return 0;
+}
+
+static int exynos4210_armclk_post_rate_change(struct exynos_cpuclk *armclk,
+			void __iomem *base)
+{
+	unsigned long mux_reg, flags;
+	unsigned long timeout = jiffies + msecs_to_jiffies(10);
+
+	spin_lock_irqsave(armclk->lock, flags);
+
+	mux_reg = readl(base + SRC_CPU);
+	writel(mux_reg & ~(1 << 16), base + SRC_CPU);
+	while (time_before(jiffies, timeout))
+		if (((readl(base + STAT_CPU) >> 16) & 0x7) == 1)
+			break;
+	if (((readl(base + STAT_CPU) >> 16) & 0x7) != 1)
+		pr_err("%s: re-parenting to mout_apll failed\n", __func__);
+
+	spin_unlock_irqrestore(armclk->lock, flags);
+	return 0;
+}
+
+/*
+ * This clock notifier is called when the frequency of the parent clock
+ * of armclk is to be changed. This notifier handles the setting up all
+ * the divider clocks, remux to temporary parent and handling the safe
+ * frequency levels when using temporary parent.
+ */
+static int exynos4210_armclk_notifier_cb(struct notifier_block *nb,
+				unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct exynos_cpuclk *armclk = to_exynos_cpuclk_nb(nb);
+	void __iomem *base =  armclk->ctrl_base + armclk->offset;
+	int err = 0;
+
+	if (event == PRE_RATE_CHANGE)
+		err = exynos4210_armclk_pre_rate_change(ndata, armclk, base);
+	else if (event == POST_RATE_CHANGE)
+		err = exynos4210_armclk_post_rate_change(armclk, base);
+
+	return notifier_from_errno(err);
+}
+
+static int exynos4210_armclk_set_rate(struct clk_hw *hw, unsigned long drate,
+					unsigned long prate)
+{
+	struct exynos_cpuclk *armclk = to_exynos_cpuclk_hw(hw);
+	void __iomem *base = armclk->ctrl_base + armclk->offset;
+	unsigned long flags;
+
+	spin_lock_irqsave(armclk->lock, flags);
+	exynos4210_set_armclk_div(base, 0);
+	spin_unlock_irqrestore(armclk->lock, flags);
+	return 0;
+}
+
+static const struct clk_ops exynos4210_armclk_clk_ops = {
+	.recalc_rate = exynos_cpuclk_recalc_rate,
+	.round_rate = exynos_cpuclk_round_rate,
+	.set_rate = exynos4210_armclk_set_rate,
+};
+
+/*
+ * parse divider configuration data from dt for all the cpu clock domain
+ * clocks in exynos4210 and compatible SoC's.
+ */
+static int __init exynos4210_armclk_parser(struct device_node *np, void **data)
+{
+	struct exynos4210_armclk_data *tdata;
+	u32 cfg[10], num_rows, row, col;
+	struct property *prop;
+	const __be32 *ptr = NULL;
+	u32 cells;
+	int len;
+
+	if (of_property_read_u32(np, "samsung,armclk-cells", &cells))
+		return -EINVAL;
+	prop = of_find_property(np, "samsung,armclk-divider-table", &len);
+	if (!prop)
+		return -EINVAL;
+	if ((len / sizeof(u32)) % cells)
+		return -EINVAL;
+	num_rows = (len / sizeof(u32)) / cells;
+
+	/* allocate a zero terminated table */
+	*data = kzalloc(sizeof(*tdata) * (num_rows + 1), GFP_KERNEL);
+	if (!*data)
+		return -ENOMEM;
+	tdata = *data;
+
+	for (row = 0; row < num_rows; row++, tdata++) {
+		for (col = 0; col < cells; col++)
+			ptr = of_prop_next_u32(prop, ptr, &cfg[col]);
+
+		tdata->prate = cfg[0] * 1000;
+		tdata->div0 = EXYNOS4210_DIV_CPU0(cfg[6], cfg[5], cfg[4],
+						cfg[3], cfg[2], cfg[1]);
+		tdata->div1 = cells == 10 ?
+				EXYNOS4210_DIV_CPU1(cfg[9], cfg[8], cfg[7]) :
+				EXYNOS4210_DIV_CPU1(0, cfg[8], cfg[7]);
+	}
+	tdata->prate = 0;
+	return 0;
+}
+
+static const struct exynos_cpuclk_soc_data exynos4210_cpuclk_soc_data = {
+	.parser = exynos4210_armclk_parser,
+	.ops = &exynos4210_armclk_clk_ops,
+	.offset = 0x14200,
+	.clk_cb = exynos4210_armclk_notifier_cb,
+};
+
+static const struct exynos_cpuclk_soc_data exynos5250_cpuclk_soc_data = {
+	.parser = exynos4210_armclk_parser,
+	.ops = &exynos4210_armclk_clk_ops,
+	.offset = 0x200,
+	.clk_cb = exynos4210_armclk_notifier_cb,
+};
+
+static const struct of_device_id exynos_clock_ids_armclk[] = {
+	{ .compatible = "samsung,exynos4210-clock",
+			.data = &exynos4210_cpuclk_soc_data, },
+	{ .compatible = "samsung,exynos4412-clock",
+			.data = &exynos4210_cpuclk_soc_data, },
+	{ .compatible = "samsung,exynos5250-clock",
+			.data = &exynos5250_cpuclk_soc_data, },
+	{ },
+};
+
+/**
+ * exynos_register_arm_clock: register arm clock with ccf.
+ * @lookup_id: armclk clock output id for the clock controller.
+ * @parent_names: name of the parent clock for armclk.
+ * @num_parents: number of parents in the @parent_names array.
+ * @base: base address of the clock controller from which armclk is generated.
+ * @np: device tree node pointer of the clock controller (optional).
+ * @ops: clock ops for this clock (optional).
+ * @lock: register access lock.
+ */
+int __init exynos_register_arm_clock(struct samsung_clk_provider *ctx,
+		unsigned int lookup_id,	const char *parent,
+		const char *alt_parent, struct device_node *np)
+{
+	const struct of_device_id *match;
+	const struct exynos_cpuclk_soc_data *data = NULL;
+
+	if (!np)
+		return -EINVAL;
+
+	match = of_match_node(exynos_clock_ids_armclk, np);
+	if (!match)
+		return -EINVAL;
+
+	data = match->data;
+	return exynos_cpuclk_register(ctx, lookup_id, "armclk", parent,
+			alt_parent, np, data);
+}
diff --git a/drivers/clk/samsung/clk.h b/drivers/clk/samsung/clk.h
index 9693b80..43da899 100644
--- a/drivers/clk/samsung/clk.h
+++ b/drivers/clk/samsung/clk.h
@@ -372,4 +372,8 @@ extern struct samsung_clk_reg_dump *samsung_clk_alloc_reg_dump(
 			const unsigned long *rdump,
 			unsigned long nr_rdump);
 
+extern int __init exynos_register_arm_clock(struct samsung_clk_provider *ctx,
+		unsigned int lookup_id,	const char *parent,
+		const char *alt_parent, struct device_node *np);
+
 #endif /* __SAMSUNG_CLK_H */
-- 
1.7.9.5