clk: st: Support for DIVMUX and PreDiv Clocks

The patch supports the DIVMUX and PreDiv clocks used by ClockGenA(s)

DIVMUX clock : Divider-Multiplexer-Gate inside ClockGenA(s)
It includes support for each channel : 3-parent Multiplexer,
Divider for each Parent, Gate to switch OFF the output channel. The
clock is implemented using generic clocks implemented in the kernel
clk_divider and clk_mux.

PreDiv clock : Fixed Divider Clock used inside ClockGenA(s) to divide
the oscillator clock by factor-of-16. The clock is implemented using
generic clocks implemented in the kernel clk_divider.

Signed-off-by: Pankaj Dev <[e-mail]>
Signed-off-by: Gabriel Fernandez <[e-mail]>
Signed-off-by: Mike Turquette <[e-mail]>

drivers/clk/Makefile

···
 obj-$(CONFIG_ARCH_SIRF)			+= sirf/
 obj-$(CONFIG_ARCH_SOCFPGA)		+= socfpga/
 obj-$(CONFIG_PLAT_SPEAR)		+= spear/
+obj-$(CONFIG_ARCH_STI)			+= st/
 obj-$(CONFIG_ARCH_SUNXI)		+= sunxi/
 obj-$(CONFIG_ARCH_TEGRA)		+= tegra/
 obj-$(CONFIG_ARCH_OMAP2PLUS)		+= ti/

drivers/clk/st/Makefile

···
+obj-y += clkgen-mux.o

drivers/clk/st/clkgen-mux.c

···
+/*
+ * clkgen-mux.c: ST GEN-MUX Clock driver
+ *
+ * Copyright (C) 2014 STMicroelectronics (R&D) Limited
+ *
+ * Authors: Stephen Gallimore <[e-mail]>
+ *	    Pankaj Dev <[e-mail]>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/of_address.h>
+#include <linux/clk-provider.h>
+
+static DEFINE_SPINLOCK(clkgena_divmux_lock);
+
+static const char ** __init clkgen_mux_get_parents(struct device_node *np,
+						       int *num_parents)
+{
+	const char **parents;
+	int nparents, i;
+
+	nparents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
+	if (WARN_ON(nparents <= 0))
+		return ERR_PTR(-EINVAL);
+
+	parents = kzalloc(nparents * sizeof(const char *), GFP_KERNEL);
+	if (!parents)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < nparents; i++)
+		parents[i] = of_clk_get_parent_name(np, i);
+
+	*num_parents = nparents;
+	return parents;
+}
+
+/**
+ * DOC: Clock mux with a programmable divider on each of its three inputs.
+ *      The mux has an input setting which effectively gates its output.
+ *
+ * Traits of this clock:
+ * prepare - clk_(un)prepare only ensures parent is (un)prepared
+ * enable - clk_enable and clk_disable are functional & control gating
+ * rate - set rate is supported
+ * parent - set/get parent
+ */
+
+#define NUM_INPUTS 3
+
+struct clkgena_divmux {
+	struct clk_hw hw;
+	/* Subclassed mux and divider structures */
+	struct clk_mux mux;
+	struct clk_divider div[NUM_INPUTS];
+	/* Enable/running feedback register bits for each input */
+	void __iomem *feedback_reg[NUM_INPUTS];
+	int feedback_bit_idx;
+
+	u8              muxsel;
+};
+
+#define to_clkgena_divmux(_hw) container_of(_hw, struct clkgena_divmux, hw)
+
+struct clkgena_divmux_data {
+	int num_outputs;
+	int mux_offset;
+	int mux_offset2;
+	int mux_start_bit;
+	int div_offsets[NUM_INPUTS];
+	int fb_offsets[NUM_INPUTS];
+	int fb_start_bit_idx;
+};
+
+#define CKGAX_CLKOPSRC_SWITCH_OFF 0x3
+
+static int clkgena_divmux_is_running(struct clkgena_divmux *mux)
+{
+	u32 regval = readl(mux->feedback_reg[mux->muxsel]);
+	u32 running = regval & BIT(mux->feedback_bit_idx);
+	return !!running;
+}
+
+static int clkgena_divmux_enable(struct clk_hw *hw)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *mux_hw = &genamux->mux.hw;
+	unsigned long timeout;
+	int ret = 0;
+
+	mux_hw->clk = hw->clk;
+
+	ret = clk_mux_ops.set_parent(mux_hw, genamux->muxsel);
+	if (ret)
+		return ret;
+
+	timeout = jiffies + msecs_to_jiffies(10);
+
+	while (!clkgena_divmux_is_running(genamux)) {
+		if (time_after(jiffies, timeout))
+			return -ETIMEDOUT;
+		cpu_relax();
+	}
+
+	return 0;
+}
+
+static void clkgena_divmux_disable(struct clk_hw *hw)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *mux_hw = &genamux->mux.hw;
+
+	mux_hw->clk = hw->clk;
+
+	clk_mux_ops.set_parent(mux_hw, CKGAX_CLKOPSRC_SWITCH_OFF);
+}
+
+static int clkgena_divmux_is_enabled(struct clk_hw *hw)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *mux_hw = &genamux->mux.hw;
+
+	mux_hw->clk = hw->clk;
+
+	return (s8)clk_mux_ops.get_parent(mux_hw) > 0;
+}
+
+u8 clkgena_divmux_get_parent(struct clk_hw *hw)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *mux_hw = &genamux->mux.hw;
+
+	mux_hw->clk = hw->clk;
+
+	genamux->muxsel = clk_mux_ops.get_parent(mux_hw);
+	if ((s8)genamux->muxsel < 0) {
+		pr_debug("%s: %s: Invalid parent, setting to default.\n",
+		      __func__, __clk_get_name(hw->clk));
+		genamux->muxsel = 0;
+	}
+
+	return genamux->muxsel;
+}
+
+static int clkgena_divmux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+
+	if (index >= CKGAX_CLKOPSRC_SWITCH_OFF)
+		return -EINVAL;
+
+	genamux->muxsel = index;
+
+	/*
+	 * If the mux is already enabled, call enable directly to set the
+	 * new mux position and wait for it to start running again. Otherwise
+	 * do nothing.
+	 */
+	if (clkgena_divmux_is_enabled(hw))
+		clkgena_divmux_enable(hw);
+
+	return 0;
+}
+
+unsigned long clkgena_divmux_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *div_hw = &genamux->div[genamux->muxsel].hw;
+
+	div_hw->clk = hw->clk;
+
+	return clk_divider_ops.recalc_rate(div_hw, parent_rate);
+}
+
+static int clkgena_divmux_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *div_hw = &genamux->div[genamux->muxsel].hw;
+
+	div_hw->clk = hw->clk;
+
+	return clk_divider_ops.set_rate(div_hw, rate, parent_rate);
+}
+
+static long clkgena_divmux_round_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long *prate)
+{
+	struct clkgena_divmux *genamux = to_clkgena_divmux(hw);
+	struct clk_hw *div_hw = &genamux->div[genamux->muxsel].hw;
+
+	div_hw->clk = hw->clk;
+
+	return clk_divider_ops.round_rate(div_hw, rate, prate);
+}
+
+static const struct clk_ops clkgena_divmux_ops = {
+	.enable = clkgena_divmux_enable,
+	.disable = clkgena_divmux_disable,
+	.is_enabled = clkgena_divmux_is_enabled,
+	.get_parent = clkgena_divmux_get_parent,
+	.set_parent = clkgena_divmux_set_parent,
+	.round_rate = clkgena_divmux_round_rate,
+	.recalc_rate = clkgena_divmux_recalc_rate,
+	.set_rate = clkgena_divmux_set_rate,
+};
+
+/**
+ * clk_register_genamux - register a genamux clock with the clock framework
+ */
+struct clk *clk_register_genamux(const char *name,
+				const char **parent_names, u8 num_parents,
+				void __iomem *reg,
+				const struct clkgena_divmux_data *muxdata,
+				u32 idx)
+{
+	/*
+	 * Fixed constants across all ClockgenA variants
+	 */
+	const int mux_width = 2;
+	const int divider_width = 5;
+	struct clkgena_divmux *genamux;
+	struct clk *clk;
+	struct clk_init_data init;
+	int i;
+
+	genamux = kzalloc(sizeof(*genamux), GFP_KERNEL);
+	if (!genamux)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clkgena_divmux_ops;
+	init.flags = CLK_IS_BASIC;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+
+	genamux->mux.lock  = &clkgena_divmux_lock;
+	genamux->mux.mask = BIT(mux_width) - 1;
+	genamux->mux.shift = muxdata->mux_start_bit + (idx * mux_width);
+	if (genamux->mux.shift > 31) {
+		/*
+		 * We have spilled into the second mux register so
+		 * adjust the register address and the bit shift accordingly
+		 */
+		genamux->mux.reg = reg + muxdata->mux_offset2;
+		genamux->mux.shift -= 32;
+	} else {
+		genamux->mux.reg   = reg + muxdata->mux_offset;
+	}
+
+	for (i = 0; i < NUM_INPUTS; i++) {
+		/*
+		 * Divider config for each input
+		 */
+		void __iomem *divbase = reg + muxdata->div_offsets[i];
+		genamux->div[i].width = divider_width;
+		genamux->div[i].reg = divbase + (idx * sizeof(u32));
+
+		/*
+		 * Mux enabled/running feedback register for each input.
+		 */
+		genamux->feedback_reg[i] = reg + muxdata->fb_offsets[i];
+	}
+
+	genamux->feedback_bit_idx = muxdata->fb_start_bit_idx + idx;
+	genamux->hw.init = &init;
+
+	clk = clk_register(NULL, &genamux->hw);
+	if (IS_ERR(clk)) {
+		kfree(genamux);
+		goto err;
+	}
+
+	pr_debug("%s: parent %s rate %lu\n",
+			__clk_get_name(clk),
+			__clk_get_name(clk_get_parent(clk)),
+			clk_get_rate(clk));
+err:
+	return clk;
+}
+
+static struct clkgena_divmux_data st_divmux_c65hs = {
+	.num_outputs = 4,
+	.mux_offset = 0x14,
+	.mux_start_bit = 0,
+	.div_offsets = { 0x800, 0x900, 0xb00 },
+	.fb_offsets = { 0x18, 0x1c, 0x20 },
+	.fb_start_bit_idx = 0,
+};
+
+static struct clkgena_divmux_data st_divmux_c65ls = {
+	.num_outputs = 14,
+	.mux_offset = 0x14,
+	.mux_offset2 = 0x24,
+	.mux_start_bit = 8,
+	.div_offsets = { 0x810, 0xa10, 0xb10 },
+	.fb_offsets = { 0x18, 0x1c, 0x20 },
+	.fb_start_bit_idx = 4,
+};
+
+static struct clkgena_divmux_data st_divmux_c32odf0 = {
+	.num_outputs = 8,
+	.mux_offset = 0x1c,
+	.mux_start_bit = 0,
+	.div_offsets = { 0x800, 0x900, 0xa60 },
+	.fb_offsets = { 0x2c, 0x24, 0x28 },
+	.fb_start_bit_idx = 0,
+};
+
+static struct clkgena_divmux_data st_divmux_c32odf1 = {
+	.num_outputs = 8,
+	.mux_offset = 0x1c,
+	.mux_start_bit = 16,
+	.div_offsets = { 0x820, 0x980, 0xa80 },
+	.fb_offsets = { 0x2c, 0x24, 0x28 },
+	.fb_start_bit_idx = 8,
+};
+
+static struct clkgena_divmux_data st_divmux_c32odf2 = {
+	.num_outputs = 8,
+	.mux_offset = 0x20,
+	.mux_start_bit = 0,
+	.div_offsets = { 0x840, 0xa20, 0xb10 },
+	.fb_offsets = { 0x2c, 0x24, 0x28 },
+	.fb_start_bit_idx = 16,
+};
+
+static struct clkgena_divmux_data st_divmux_c32odf3 = {
+	.num_outputs = 8,
+	.mux_offset = 0x20,
+	.mux_start_bit = 16,
+	.div_offsets = { 0x860, 0xa40, 0xb30 },
+	.fb_offsets = { 0x2c, 0x24, 0x28 },
+	.fb_start_bit_idx = 24,
+};
+
+static struct of_device_id clkgena_divmux_of_match[] = {
+	{
+		.compatible = "st,clkgena-divmux-c65-hs",
+		.data = &st_divmux_c65hs,
+	},
+	{
+		.compatible = "st,clkgena-divmux-c65-ls",
+		.data = &st_divmux_c65ls,
+	},
+	{
+		.compatible = "st,clkgena-divmux-c32-odf0",
+		.data = &st_divmux_c32odf0,
+	},
+	{
+		.compatible = "st,clkgena-divmux-c32-odf1",
+		.data = &st_divmux_c32odf1,
+	},
+	{
+		.compatible = "st,clkgena-divmux-c32-odf2",
+		.data = &st_divmux_c32odf2,
+	},
+	{
+		.compatible = "st,clkgena-divmux-c32-odf3",
+		.data = &st_divmux_c32odf3,
+	},
+	{}
+};
+
+static void __iomem * __init clkgen_get_register_base(
+				struct device_node *np)
+{
+	struct device_node *pnode;
+	void __iomem *reg = NULL;
+
+	pnode = of_get_parent(np);
+	if (!pnode)
+		return NULL;
+
+	reg = of_iomap(pnode, 0);
+
+	of_node_put(pnode);
+	return reg;
+}
+
+void __init st_of_clkgena_divmux_setup(struct device_node *np)
+{
+	const struct of_device_id *match;
+	const struct clkgena_divmux_data *data;
+	struct clk_onecell_data *clk_data;
+	void __iomem *reg;
+	const char **parents;
+	int num_parents = 0, i;
+
+	match = of_match_node(clkgena_divmux_of_match, np);
+	if (WARN_ON(!match))
+		return;
+
+	data = (struct clkgena_divmux_data *)match->data;
+
+	reg = clkgen_get_register_base(np);
+	if (!reg)
+		return;
+
+	parents = clkgen_mux_get_parents(np, &num_parents);
+	if (IS_ERR(parents))
+		return;
+
+	clk_data = kzalloc(sizeof(*clk_data), GFP_KERNEL);
+	if (!clk_data)
+		goto err;
+
+	clk_data->clk_num = data->num_outputs;
+	clk_data->clks = kzalloc(clk_data->clk_num * sizeof(struct clk *),
+				 GFP_KERNEL);
+
+	if (!clk_data->clks)
+		goto err;
+
+	for (i = 0; i < clk_data->clk_num; i++) {
+		struct clk *clk;
+		const char *clk_name;
+
+		if (of_property_read_string_index(np, "clock-output-names",
+						  i, &clk_name))
+			break;
+
+		/*
+		 * If we read an empty clock name then the output is unused
+		 */
+		if (*clk_name == '\0')
+			continue;
+
+		clk = clk_register_genamux(clk_name, parents, num_parents,
+					   reg, data, i);
+
+		if (IS_ERR(clk))
+			goto err;
+
+		clk_data->clks[i] = clk;
+	}
+
+	kfree(parents);
+
+	of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
+	return;
+err:
+	if (clk_data)
+		kfree(clk_data->clks);
+
+	kfree(clk_data);
+	kfree(parents);
+}
+CLK_OF_DECLARE(clkgenadivmux, "st,clkgena-divmux", st_of_clkgena_divmux_setup);
+
+struct clkgena_prediv_data {
+	u32 offset;
+	u8 shift;
+	struct clk_div_table *table;
+};
+
+static struct clk_div_table prediv_table16[] = {
+	{ .val = 0, .div = 1 },
+	{ .val = 1, .div = 16 },
+	{ .div = 0 },
+};
+
+static struct clkgena_prediv_data prediv_c65_data = {
+	.offset = 0x4c,
+	.shift = 31,
+	.table = prediv_table16,
+};
+
+static struct clkgena_prediv_data prediv_c32_data = {
+	.offset = 0x50,
+	.shift = 1,
+	.table = prediv_table16,
+};
+
+static struct of_device_id clkgena_prediv_of_match[] = {
+	{ .compatible = "st,clkgena-prediv-c65", .data = &prediv_c65_data },
+	{ .compatible = "st,clkgena-prediv-c32", .data = &prediv_c32_data },
+	{}
+};
+
+void __init st_of_clkgena_prediv_setup(struct device_node *np)
+{
+	const struct of_device_id *match;
+	void __iomem *reg;
+	const char *parent_name, *clk_name;
+	struct clk *clk;
+	struct clkgena_prediv_data *data;
+
+	match = of_match_node(clkgena_prediv_of_match, np);
+	if (!match) {
+		pr_err("%s: No matching data\n", __func__);
+		return;
+	}
+
+	data = (struct clkgena_prediv_data *)match->data;
+
+	reg = clkgen_get_register_base(np);
+	if (!reg)
+		return;
+
+	parent_name = of_clk_get_parent_name(np, 0);
+	if (!parent_name)
+		return;
+
+	if (of_property_read_string_index(np, "clock-output-names",
+					  0, &clk_name))
+		return;
+
+	clk = clk_register_divider_table(NULL, clk_name, parent_name, 0,
+					 reg + data->offset, data->shift, 1,
+					 0, data->table, NULL);
+	if (IS_ERR(clk))
+		return;
+
+	of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	pr_debug("%s: parent %s rate %u\n",
+		__clk_get_name(clk),
+		__clk_get_name(clk_get_parent(clk)),
+		(unsigned int)clk_get_rate(clk));
+
+	return;
+}
+CLK_OF_DECLARE(clkgenaprediv, "st,clkgena-prediv", st_of_clkgena_prediv_setup);