clk: ti: Add support for FAPLL on dm816x

On dm816x the clocks are sourced from a FAPLL (Flying Adder PLL)
that does not seem to be used on the other omap variants.

There are four instances of the FAPLL on dm816x that each have three
to seven child synthesizers.

I've set up the FAPLL as a single fapll.c driver. Later on we could
potentially have the PLL code generic. To do that, we would have to
consider the following:

1. Setting the PLL to bypass mode also sets the child synthesizers
   into bypass mode. As the bypass rate can also be generated by
   the PLL in regular mode, there's no way for the child synthesizers
   to detect the bypass mode based on the parent clock rate.

2. The PLL registers control the power for each of the child
   syntheriser.

Note that the clocks are currently still missing the set_rate
implementation so things are still running based on the bootloader
values. That's OK for now as most of the outputs have dividers and
those can be set using the existing TI component clock code.

I have verified that the extclk rates are correct for a few clocks,
so adding the set_rate support should be fairly trivial later on.

This code is partially based on the TI81XX-LINUX-PSP-04.04.00.02
patches published at:

http://downloads.ti.com/dsps/dsps_public_sw/psp/LinuxPSP/TI81XX_04_04/04_04_00_02/index_FDS.html

Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

Documentation/devicetree/bindings/clock/ti/fapll.txt

+Binding for Texas Instruments FAPLL clock.
+
+Binding status: Unstable - ABI compatibility may be broken in the future
+
+This binding uses the common clock binding[1]. It assumes a
+register-mapped FAPLL with usually two selectable input clocks
+(reference clock and bypass clock), and one or more child
+syntesizers.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "ti,dm816-fapll-clock"
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link phandles of parent clocks (clk-ref and clk-bypass)
+- reg : address and length of the register set for controlling the FAPLL.
+
+Examples:
+	main_fapll: main_fapll {
+		#clock-cells = <1>;
+		compatible = "ti,dm816-fapll-clock";
+		reg = <0x400 0x40>;
+		clocks = <&sys_clkin_ck &sys_clkin_ck>;
+		clock-indices = <1>, <2>, <3>, <4>, <5>,
+				<6>, <7>;
+		clock-output-names = "main_pll_clk1",
+				     "main_pll_clk2",
+				     "main_pll_clk3",
+				     "main_pll_clk4",
+				     "main_pll_clk5",
+				     "main_pll_clk6",
+				     "main_pll_clk7";
+	};

drivers/clk/ti/Makefile

@@ -3,6 +3,7 @@ obj-y					+= clk.o autoidle.o clockdomain.o
 clk-common				= dpll.o composite.o divider.o gate.o \
 					  fixed-factor.o mux.o apll.o
 obj-$(CONFIG_SOC_AM33XX)		+= $(clk-common) clk-33xx.o
+obj-$(CONFIG_SOC_TI81XX)		+= $(clk-common) fapll.o
 obj-$(CONFIG_ARCH_OMAP2)		+= $(clk-common) interface.o clk-2xxx.o
 obj-$(CONFIG_ARCH_OMAP3)		+= $(clk-common) interface.o clk-3xxx.o
 obj-$(CONFIG_ARCH_OMAP4)		+= $(clk-common) clk-44xx.o

drivers/clk/ti/fapll.c

+/*
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/clk/ti.h>
+#include <asm/div64.h>
+
+/* FAPLL Control Register PLL_CTRL */
+#define FAPLL_MAIN_LOCK		BIT(7)
+#define FAPLL_MAIN_PLLEN	BIT(3)
+#define FAPLL_MAIN_BP		BIT(2)
+#define FAPLL_MAIN_LOC_CTL	BIT(0)
+
+/* FAPLL powerdown register PWD */
+#define FAPLL_PWD_OFFSET	4
+
+#define MAX_FAPLL_OUTPUTS	7
+#define FAPLL_MAX_RETRIES	1000
+
+#define to_fapll(_hw)		container_of(_hw, struct fapll_data, hw)
+#define to_synth(_hw)		container_of(_hw, struct fapll_synth, hw)
+
+/* The bypass bit is inverted on the ddr_pll.. */
+#define fapll_is_ddr_pll(va)	(((u32)(va) & 0xffff) == 0x0440)
+
+/*
+ * The audio_pll_clk1 input is hard wired to the 27MHz bypass clock,
+ * and the audio_pll_clk1 synthesizer is hardwared to 32KiHz output.
+ */
+#define is_ddr_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x044c)
+#define is_audio_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x04a8)
+
+/* Synthesizer divider register */
+#define SYNTH_LDMDIV1		BIT(8)
+
+/* Synthesizer frequency register */
+#define SYNTH_LDFREQ		BIT(31)
+
+struct fapll_data {
+	struct clk_hw hw;
+	void __iomem *base;
+	const char *name;
+	struct clk *clk_ref;
+	struct clk *clk_bypass;
+	struct clk_onecell_data outputs;
+	bool bypass_bit_inverted;
+};
+
+struct fapll_synth {
+	struct clk_hw hw;
+	struct fapll_data *fd;
+	int index;
+	void __iomem *freq;
+	void __iomem *div;
+	const char *name;
+	struct clk *clk_pll;
+};
+
+static bool ti_fapll_clock_is_bypass(struct fapll_data *fd)
+{
+	u32 v = readl_relaxed(fd->base);
+
+	if (fd->bypass_bit_inverted)
+		return !(v & FAPLL_MAIN_BP);
+	else
+		return !!(v & FAPLL_MAIN_BP);
+}
+
+static int ti_fapll_enable(struct clk_hw *hw)
+{
+	struct fapll_data *fd = to_fapll(hw);
+	u32 v = readl_relaxed(fd->base);
+
+	v |= (1 << FAPLL_MAIN_PLLEN);
+	writel_relaxed(v, fd->base);
+
+	return 0;
+}
+
+static void ti_fapll_disable(struct clk_hw *hw)
+{
+	struct fapll_data *fd = to_fapll(hw);
+	u32 v = readl_relaxed(fd->base);
+
+	v &= ~(1 << FAPLL_MAIN_PLLEN);
+	writel_relaxed(v, fd->base);
+}
+
+static int ti_fapll_is_enabled(struct clk_hw *hw)
+{
+	struct fapll_data *fd = to_fapll(hw);
+	u32 v = readl_relaxed(fd->base);
+
+	return v & (1 << FAPLL_MAIN_PLLEN);
+}
+
+static unsigned long ti_fapll_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	struct fapll_data *fd = to_fapll(hw);
+	u32 fapll_n, fapll_p, v;
+	long long rate;
+
+	if (ti_fapll_clock_is_bypass(fd))
+		return parent_rate;
+
+	rate = parent_rate;
+
+	/* PLL pre-divider is P and multiplier is N */
+	v = readl_relaxed(fd->base);
+	fapll_p = (v >> 8) & 0xff;
+	if (fapll_p)
+		do_div(rate, fapll_p);
+	fapll_n = v >> 16;
+	if (fapll_n)
+		rate *= fapll_n;
+
+	return rate;
+}
+
+static u8 ti_fapll_get_parent(struct clk_hw *hw)
+{
+	struct fapll_data *fd = to_fapll(hw);
+
+	if (ti_fapll_clock_is_bypass(fd))
+		return 1;
+
+	return 0;
+}
+
+static struct clk_ops ti_fapll_ops = {
+	.enable = ti_fapll_enable,
+	.disable = ti_fapll_disable,
+	.is_enabled = ti_fapll_is_enabled,
+	.recalc_rate = ti_fapll_recalc_rate,
+	.get_parent = ti_fapll_get_parent,
+};
+
+static int ti_fapll_synth_enable(struct clk_hw *hw)
+{
+	struct fapll_synth *synth = to_synth(hw);
+	u32 v = readl_relaxed(synth->fd->base + FAPLL_PWD_OFFSET);
+
+	v &= ~(1 << synth->index);
+	writel_relaxed(v, synth->fd->base + FAPLL_PWD_OFFSET);
+
+	return 0;
+}
+
+static void ti_fapll_synth_disable(struct clk_hw *hw)
+{
+	struct fapll_synth *synth = to_synth(hw);
+	u32 v = readl_relaxed(synth->fd->base + FAPLL_PWD_OFFSET);
+
+	v |= 1 << synth->index;
+	writel_relaxed(v, synth->fd->base + FAPLL_PWD_OFFSET);
+}
+
+static int ti_fapll_synth_is_enabled(struct clk_hw *hw)
+{
+	struct fapll_synth *synth = to_synth(hw);
+	u32 v = readl_relaxed(synth->fd->base + FAPLL_PWD_OFFSET);
+
+	return !(v & (1 << synth->index));
+}
+
+/*
+ * See dm816x TRM chapter 1.10.3 Flying Adder PLL fore more info
+ */
+static unsigned long ti_fapll_synth_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct fapll_synth *synth = to_synth(hw);
+	u32 synth_div_m;
+	long long rate;
+
+	/* The audio_pll_clk1 is hardwired to produce 32.768KiHz clock */
+	if (!synth->div)
+		return 32768;
+
+	/*
+	 * PLL in bypass sets the synths in bypass mode too. The PLL rate
+	 * can be also be set to 27MHz, so we can't use parent_rate to
+	 * check for bypass mode.
+	 */
+	if (ti_fapll_clock_is_bypass(synth->fd))
+		return parent_rate;
+
+	rate = parent_rate;
+
+	/*
+	 * Synth frequency integer and fractional divider.
+	 * Note that the phase output K is 8, so the result needs
+	 * to be multiplied by 8.
+	 */
+	if (synth->freq) {
+		u32 v, synth_int_div, synth_frac_div, synth_div_freq;
+
+		v = readl_relaxed(synth->freq);
+		synth_int_div = (v >> 24) & 0xf;
+		synth_frac_div = v & 0xffffff;
+		synth_div_freq = (synth_int_div * 10000000) + synth_frac_div;
+		rate *= 10000000;
+		do_div(rate, synth_div_freq);
+		rate *= 8;
+	}
+
+	/* Synth ost-divider M */
+	synth_div_m = readl_relaxed(synth->div) & 0xff;
+	do_div(rate, synth_div_m);
+
+	return rate;
+}
+
+static struct clk_ops ti_fapll_synt_ops = {
+	.enable = ti_fapll_synth_enable,
+	.disable = ti_fapll_synth_disable,
+	.is_enabled = ti_fapll_synth_is_enabled,
+	.recalc_rate = ti_fapll_synth_recalc_rate,
+};
+
+static struct clk * __init ti_fapll_synth_setup(struct fapll_data *fd,
+						void __iomem *freq,
+						void __iomem *div,
+						int index,
+						const char *name,
+						const char *parent,
+						struct clk *pll_clk)
+{
+	struct clk_init_data *init;
+	struct fapll_synth *synth;
+
+	init = kzalloc(sizeof(*init), GFP_KERNEL);
+	if (!init)
+		return ERR_PTR(-ENOMEM);
+
+	init->ops = &ti_fapll_synt_ops;
+	init->name = name;
+	init->parent_names = &parent;
+	init->num_parents = 1;
+
+	synth = kzalloc(sizeof(*synth), GFP_KERNEL);
+	if (!synth)
+		goto free;
+
+	synth->fd = fd;
+	synth->index = index;
+	synth->freq = freq;
+	synth->div = div;
+	synth->name = name;
+	synth->hw.init = init;
+	synth->clk_pll = pll_clk;
+
+	return clk_register(NULL, &synth->hw);
+
+free:
+	kfree(synth);
+	kfree(init);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static void __init ti_fapll_setup(struct device_node *node)
+{
+	struct fapll_data *fd;
+	struct clk_init_data *init = NULL;
+	const char *parent_name[2];
+	struct clk *pll_clk;
+	int i;
+
+	fd = kzalloc(sizeof(*fd), GFP_KERNEL);
+	if (!fd)
+		return;
+
+	fd->outputs.clks = kzalloc(sizeof(struct clk *) *
+				   MAX_FAPLL_OUTPUTS + 1,
+				   GFP_KERNEL);
+	if (!fd->outputs.clks)
+		goto free;
+
+	init = kzalloc(sizeof(*init), GFP_KERNEL);
+	if (!init)
+		goto free;
+
+	init->ops = &ti_fapll_ops;
+	init->name = node->name;
+
+	init->num_parents = of_clk_get_parent_count(node);
+	if (init->num_parents != 2) {
+		pr_err("%s must have two parents\n", node->name);
+		goto free;
+	}
+
+	parent_name[0] = of_clk_get_parent_name(node, 0);
+	parent_name[1] = of_clk_get_parent_name(node, 1);
+	init->parent_names = parent_name;
+
+	fd->clk_ref = of_clk_get(node, 0);
+	if (IS_ERR(fd->clk_ref)) {
+		pr_err("%s could not get clk_ref\n", node->name);
+		goto free;
+	}
+
+	fd->clk_bypass = of_clk_get(node, 1);
+	if (IS_ERR(fd->clk_bypass)) {
+		pr_err("%s could not get clk_bypass\n", node->name);
+		goto free;
+	}
+
+	fd->base = of_iomap(node, 0);
+	if (!fd->base) {
+		pr_err("%s could not get IO base\n", node->name);
+		goto free;
+	}
+
+	if (fapll_is_ddr_pll(fd->base))
+		fd->bypass_bit_inverted = true;
+
+	fd->name = node->name;
+	fd->hw.init = init;
+
+	/* Register the parent PLL */
+	pll_clk = clk_register(NULL, &fd->hw);
+	if (IS_ERR(pll_clk))
+		goto unmap;
+
+	fd->outputs.clks[0] = pll_clk;
+	fd->outputs.clk_num++;
+
+	/*
+	 * Set up the child synthesizers starting at index 1 as the
+	 * PLL output is at index 0. We need to check the clock-indices
+	 * for numbering in case there are holes in the synth mapping,
+	 * and then probe the synth register to see if it has a FREQ
+	 * register available.
+	 */
+	for (i = 0; i < MAX_FAPLL_OUTPUTS; i++) {
+		const char *output_name;
+		void __iomem *freq, *div;
+		struct clk *synth_clk;
+		int output_instance;
+		u32 v;
+
+		if (of_property_read_string_index(node, "clock-output-names",
+						  i, &output_name))
+			continue;
+
+		if (of_property_read_u32_index(node, "clock-indices", i,
+					       &output_instance))
+			output_instance = i;
+
+		freq = fd->base + (output_instance * 8);
+		div = freq + 4;
+
+		/* Check for hardwired audio_pll_clk1 */
+		if (is_audio_pll_clk1(freq)) {
+			freq = 0;
+			div = 0;
+		} else {
+			/* Does the synthesizer have a FREQ register? */
+			v = readl_relaxed(freq);
+			if (!v)
+				freq = 0;
+		}
+		synth_clk = ti_fapll_synth_setup(fd, freq, div, output_instance,
+						 output_name, node->name,
+						 pll_clk);
+		if (IS_ERR(synth_clk))
+			continue;
+
+		fd->outputs.clks[output_instance] = synth_clk;
+		fd->outputs.clk_num++;
+
+		clk_register_clkdev(synth_clk, output_name, NULL);
+	}
+
+	/* Register the child synthesizers as the FAPLL outputs */
+	of_clk_add_provider(node, of_clk_src_onecell_get, &fd->outputs);
+	/* Add clock alias for the outputs */
+
+	kfree(init);
+
+	return;
+
+unmap:
+	iounmap(fd->base);
+free:
+	if (fd->clk_bypass)
+		clk_put(fd->clk_bypass);
+	if (fd->clk_ref)
+		clk_put(fd->clk_ref);
+	kfree(fd->outputs.clks);
+	kfree(fd);
+	kfree(init);
+}
+
+CLK_OF_DECLARE(ti_fapll_clock, "ti,dm816-fapll-clock", ti_fapll_setup);