clk/axs10x: Add I2S PLL clock driver

The ARC SDP I2S clock can be programmed using a
specific PLL.

This patch has the goal of adding a clock driver
that programs this PLL.

At this moment the rate values are hardcoded in
a table but in the future it would be ideal to
use a function which determines the PLL values
given the desired rate.
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Documentation/devicetree/bindings/clock/axs10x-i2s-pll-clock.txt

+Binding for the AXS10X I2S PLL clock
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible: shall be "snps,axs10x-i2s-pll-clock"
+- reg : address and length of the I2S PLL register set.
+- clocks: shall be the input parent clock phandle for the PLL.
+- #clock-cells: from common clock binding; Should always be set to 0.
+
+Example:
+	pll_clock: pll_clock {
+		compatible = "fixed-clock";
+		clock-frequency = <27000000>;
+		#clock-cells = <0>;
+	};
+
+	i2s_clock@100a0 {
+		compatible = "snps,axs10x-i2s-pll-clock";
+		reg = <0x100a0 0x10>;
+		clocks = <&pll_clock>;
+		#clock-cells = <0>;
+	};

drivers/clk/Makefile

@@ -86,3 +86,4 @@ obj-$(CONFIG_X86)			+= x86/
 obj-$(CONFIG_ARCH_ZX)			+= zte/
 obj-$(CONFIG_ARCH_ZYNQ)			+= zynq/
 obj-$(CONFIG_H8300)		+= h8300/
+obj-$(CONFIG_ARC_PLAT_AXS10X)		+= axs10x/

drivers/clk/axs10x/Makefile

+obj-y += i2s_pll_clock.o

drivers/clk/axs10x/i2s_pll_clock.c

+/*
+ * Synopsys AXS10X SDP I2S PLL clock driver
+ *
+ * Copyright (C) 2016 Synopsys
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+/* PLL registers addresses */
+#define PLL_IDIV_REG	0x0
+#define PLL_FBDIV_REG	0x4
+#define PLL_ODIV0_REG	0x8
+#define PLL_ODIV1_REG	0xC
+
+struct i2s_pll_cfg {
+	unsigned int rate;
+	unsigned int idiv;
+	unsigned int fbdiv;
+	unsigned int odiv0;
+	unsigned int odiv1;
+};
+
+static const struct i2s_pll_cfg i2s_pll_cfg_27m[] = {
+	/* 27 Mhz */
+	{ 1024000, 0x104, 0x451, 0x10E38, 0x2000 },
+	{ 1411200, 0x104, 0x596, 0x10D35, 0x2000 },
+	{ 1536000, 0x208, 0xA28, 0x10B2C, 0x2000 },
+	{ 2048000, 0x82, 0x451, 0x10E38, 0x2000 },
+	{ 2822400, 0x82, 0x596, 0x10D35, 0x2000 },
+	{ 3072000, 0x104, 0xA28, 0x10B2C, 0x2000 },
+	{ 2116800, 0x82, 0x3CF, 0x10C30, 0x2000 },
+	{ 2304000, 0x104, 0x79E, 0x10B2C, 0x2000 },
+	{ 0, 0, 0, 0, 0 },
+};
+
+static const struct i2s_pll_cfg i2s_pll_cfg_28m[] = {
+	/* 28.224 Mhz */
+	{ 1024000, 0x82, 0x105, 0x107DF, 0x2000 },
+	{ 1411200, 0x28A, 0x1, 0x10001, 0x2000 },
+	{ 1536000, 0xA28, 0x187, 0x10042, 0x2000 },
+	{ 2048000, 0x41, 0x105, 0x107DF, 0x2000 },
+	{ 2822400, 0x145, 0x1, 0x10001, 0x2000 },
+	{ 3072000, 0x514, 0x187, 0x10042, 0x2000 },
+	{ 2116800, 0x514, 0x42, 0x10001, 0x2000 },
+	{ 2304000, 0x619, 0x82, 0x10001, 0x2000 },
+	{ 0, 0, 0, 0, 0 },
+};
+
+struct i2s_pll_clk {
+	void __iomem *base;
+	struct clk_hw hw;
+	struct device *dev;
+};
+
+static inline void i2s_pll_write(struct i2s_pll_clk *clk, unsigned int reg,
+		unsigned int val)
+{
+	writel_relaxed(val, clk->base + reg);
+}
+
+static inline unsigned int i2s_pll_read(struct i2s_pll_clk *clk,
+		unsigned int reg)
+{
+	return readl_relaxed(clk->base + reg);
+}
+
+static inline struct i2s_pll_clk *to_i2s_pll_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct i2s_pll_clk, hw);
+}
+
+static inline unsigned int i2s_pll_get_value(unsigned int val)
+{
+	return (val & 0x3F) + ((val >> 6) & 0x3F);
+}
+
+static const struct i2s_pll_cfg *i2s_pll_get_cfg(unsigned long prate)
+{
+	switch (prate) {
+	case 27000000:
+		return i2s_pll_cfg_27m;
+	case 28224000:
+		return i2s_pll_cfg_28m;
+	default:
+		return NULL;
+	}
+}
+
+static unsigned long i2s_pll_recalc_rate(struct clk_hw *hw,
+			unsigned long parent_rate)
+{
+	struct i2s_pll_clk *clk = to_i2s_pll_clk(hw);
+	unsigned int idiv, fbdiv, odiv;
+
+	idiv = i2s_pll_get_value(i2s_pll_read(clk, PLL_IDIV_REG));
+	fbdiv = i2s_pll_get_value(i2s_pll_read(clk, PLL_FBDIV_REG));
+	odiv = i2s_pll_get_value(i2s_pll_read(clk, PLL_ODIV0_REG));
+
+	return ((parent_rate / idiv) * fbdiv) / odiv;
+}
+
+static long i2s_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long *prate)
+{
+	struct i2s_pll_clk *clk = to_i2s_pll_clk(hw);
+	const struct i2s_pll_cfg *pll_cfg = i2s_pll_get_cfg(*prate);
+	int i;
+
+	if (!pll_cfg) {
+		dev_err(clk->dev, "invalid parent rate=%ld\n", *prate);
+		return -EINVAL;
+	}
+
+	for (i = 0; pll_cfg[i].rate != 0; i++)
+		if (pll_cfg[i].rate == rate)
+			return rate;
+
+	return -EINVAL;
+}
+
+static int i2s_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long parent_rate)
+{
+	struct i2s_pll_clk *clk = to_i2s_pll_clk(hw);
+	const struct i2s_pll_cfg *pll_cfg = i2s_pll_get_cfg(parent_rate);
+	int i;
+
+	if (!pll_cfg) {
+		dev_err(clk->dev, "invalid parent rate=%ld\n", parent_rate);
+		return -EINVAL;
+	}
+
+	for (i = 0; pll_cfg[i].rate != 0; i++) {
+		if (pll_cfg[i].rate == rate) {
+			i2s_pll_write(clk, PLL_IDIV_REG, pll_cfg[i].idiv);
+			i2s_pll_write(clk, PLL_FBDIV_REG, pll_cfg[i].fbdiv);
+			i2s_pll_write(clk, PLL_ODIV0_REG, pll_cfg[i].odiv0);
+			i2s_pll_write(clk, PLL_ODIV1_REG, pll_cfg[i].odiv1);
+			return 0;
+		}
+	}
+
+	dev_err(clk->dev, "invalid rate=%ld, parent_rate=%ld\n", rate,
+			parent_rate);
+	return -EINVAL;
+}
+
+static const struct clk_ops i2s_pll_ops = {
+	.recalc_rate = i2s_pll_recalc_rate,
+	.round_rate = i2s_pll_round_rate,
+	.set_rate = i2s_pll_set_rate,
+};
+
+static int i2s_pll_clk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	const char *clk_name;
+	const char *parent_name;
+	struct clk *clk;
+	struct i2s_pll_clk *pll_clk;
+	struct clk_init_data init;
+	struct resource *mem;
+
+	pll_clk = devm_kzalloc(dev, sizeof(*pll_clk), GFP_KERNEL);
+	if (!pll_clk)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pll_clk->base = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(pll_clk->base))
+		return PTR_ERR(pll_clk->base);
+
+	clk_name = node->name;
+	init.name = clk_name;
+	init.ops = &i2s_pll_ops;
+	parent_name = of_clk_get_parent_name(node, 0);
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+	pll_clk->hw.init = &init;
+	pll_clk->dev = dev;
+
+	clk = devm_clk_register(dev, &pll_clk->hw);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "failed to register %s clock (%ld)\n",
+				clk_name, PTR_ERR(clk));
+		return PTR_ERR(clk);
+	}
+
+	return of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+
+static int i2s_pll_clk_remove(struct platform_device *pdev)
+{
+	of_clk_del_provider(pdev->dev.of_node);
+	return 0;
+}
+
+static const struct of_device_id i2s_pll_clk_id[] = {
+	{ .compatible = "snps,axs10x-i2s-pll-clock", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, i2s_pll_clk_id);
+
+static struct platform_driver i2s_pll_clk_driver = {
+	.driver = {
+		.name = "axs10x-i2s-pll-clock",
+		.of_match_table = i2s_pll_clk_id,
+	},
+	.probe = i2s_pll_clk_probe,
+	.remove = i2s_pll_clk_remove,
+};
+module_platform_driver(i2s_pll_clk_driver);
+
+MODULE_AUTHOR("Jose Abreu <joabreu@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys AXS10X SDP I2S PLL Clock Driver");
+MODULE_LICENSE("GPL v2");