clk: qcom: Add spmi_pmic clock divider support

Clkdiv module provides a clock output on the PMIC with CXO as
the source. This clock can be routed through PMIC GPIOs. Add
a device driver to configure this clkdiv module.
Signed-off-by: NTirupathi Reddy <tirupath@codeaurora.org>
[sboyd: Simplified code and moved to devm clk provider APIs]
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>

drivers/clk/qcom/Kconfig

@@ -196,3 +196,12 @@ config MSM_MMCC_8996
 	  Support for the multimedia clock controller on msm8996 devices.
 	  Say Y if you want to support multimedia devices such as display,
 	  graphics, video encode/decode, camera, etc.
+
+config SPMI_PMIC_CLKDIV
+	tristate "SPMI PMIC clkdiv Support"
+	depends on (COMMON_CLK_QCOM && SPMI) || COMPILE_TEST
+	help
+	  This driver supports the clkdiv functionality on the Qualcomm
+	  Technologies, Inc. SPMI PMIC. It configures the frequency of
+	  clkdiv outputs of the PMIC. These clocks are typically wired
+	  through alternate functions on GPIO pins.

drivers/clk/qcom/Makefile

@@ -34,3 +34,4 @@ obj-$(CONFIG_MSM_MMCC_8974) += mmcc-msm8974.o
 obj-$(CONFIG_MSM_MMCC_8996) += mmcc-msm8996.o
 obj-$(CONFIG_QCOM_CLK_RPM) += clk-rpm.o
 obj-$(CONFIG_QCOM_CLK_SMD_RPM) += clk-smd-rpm.o
+obj-$(CONFIG_SPMI_PMIC_CLKDIV) += clk-spmi-pmic-div.o

drivers/clk/qcom/clk-spmi-pmic-div.c

+/* Copyright (c) 2017, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define REG_DIV_CTL1			0x43
+#define DIV_CTL1_DIV_FACTOR_MASK	GENMASK(2, 0)
+
+#define REG_EN_CTL			0x46
+#define REG_EN_MASK			BIT(7)
+
+struct clkdiv {
+	struct regmap		*regmap;
+	u16			base;
+	spinlock_t		lock;
+
+	struct clk_hw		hw;
+	unsigned int		cxo_period_ns;
+};
+
+static inline struct clkdiv *to_clkdiv(struct clk_hw *hw)
+{
+	return container_of(hw, struct clkdiv, hw);
+}
+
+static inline unsigned int div_factor_to_div(unsigned int div_factor)
+{
+	if (!div_factor)
+		div_factor = 1;
+
+	return 1 << (div_factor - 1);
+}
+
+static inline unsigned int div_to_div_factor(unsigned int div)
+{
+	return min(ilog2(div) + 1, 7);
+}
+
+static bool is_spmi_pmic_clkdiv_enabled(struct clkdiv *clkdiv)
+{
+	unsigned int val = 0;
+
+	regmap_read(clkdiv->regmap, clkdiv->base + REG_EN_CTL, &val);
+
+	return val & REG_EN_MASK;
+}
+
+static int
+__spmi_pmic_clkdiv_set_enable_state(struct clkdiv *clkdiv, bool enable,
+				    unsigned int div_factor)
+{
+	int ret;
+	unsigned int ns = clkdiv->cxo_period_ns;
+	unsigned int div = div_factor_to_div(div_factor);
+
+	ret = regmap_update_bits(clkdiv->regmap, clkdiv->base + REG_EN_CTL,
+				 REG_EN_MASK, enable ? REG_EN_MASK : 0);
+	if (ret)
+		return ret;
+
+	if (enable)
+		ndelay((2 + 3 * div) * ns);
+	else
+		ndelay(3 * div * ns);
+
+	return 0;
+}
+
+static int spmi_pmic_clkdiv_set_enable_state(struct clkdiv *clkdiv, bool enable)
+{
+	unsigned int div_factor;
+
+	regmap_read(clkdiv->regmap, clkdiv->base + REG_DIV_CTL1, &div_factor);
+	div_factor &= DIV_CTL1_DIV_FACTOR_MASK;
+
+	return __spmi_pmic_clkdiv_set_enable_state(clkdiv, enable, div_factor);
+}
+
+static int clk_spmi_pmic_div_enable(struct clk_hw *hw)
+{
+	struct clkdiv *clkdiv = to_clkdiv(hw);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&clkdiv->lock, flags);
+	ret = spmi_pmic_clkdiv_set_enable_state(clkdiv, true);
+	spin_unlock_irqrestore(&clkdiv->lock, flags);
+
+	return ret;
+}
+
+static void clk_spmi_pmic_div_disable(struct clk_hw *hw)
+{
+	struct clkdiv *clkdiv = to_clkdiv(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(&clkdiv->lock, flags);
+	spmi_pmic_clkdiv_set_enable_state(clkdiv, false);
+	spin_unlock_irqrestore(&clkdiv->lock, flags);
+}
+
+static long clk_spmi_pmic_div_round_rate(struct clk_hw *hw, unsigned long rate,
+					 unsigned long *parent_rate)
+{
+	unsigned int div, div_factor;
+
+	div = DIV_ROUND_UP(*parent_rate, rate);
+	div_factor = div_to_div_factor(div);
+	div = div_factor_to_div(div_factor);
+
+	return *parent_rate / div;
+}
+
+static unsigned long
+clk_spmi_pmic_div_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct clkdiv *clkdiv = to_clkdiv(hw);
+	unsigned int div_factor;
+
+	regmap_read(clkdiv->regmap, clkdiv->base + REG_DIV_CTL1, &div_factor);
+	div_factor &= DIV_CTL1_DIV_FACTOR_MASK;
+
+	return parent_rate / div_factor_to_div(div_factor);
+}
+
+static int clk_spmi_pmic_div_set_rate(struct clk_hw *hw, unsigned long rate,
+				      unsigned long parent_rate)
+{
+	struct clkdiv *clkdiv = to_clkdiv(hw);
+	unsigned int div_factor = div_to_div_factor(parent_rate / rate);
+	unsigned long flags;
+	bool enabled;
+	int ret;
+
+	spin_lock_irqsave(&clkdiv->lock, flags);
+	enabled = is_spmi_pmic_clkdiv_enabled(clkdiv);
+	if (enabled) {
+		ret = spmi_pmic_clkdiv_set_enable_state(clkdiv, false);
+		if (ret)
+			goto unlock;
+	}
+
+	ret = regmap_update_bits(clkdiv->regmap, clkdiv->base + REG_DIV_CTL1,
+				 DIV_CTL1_DIV_FACTOR_MASK, div_factor);
+	if (ret)
+		goto unlock;
+
+	if (enabled)
+		ret = __spmi_pmic_clkdiv_set_enable_state(clkdiv, true,
+							  div_factor);
+
+unlock:
+	spin_unlock_irqrestore(&clkdiv->lock, flags);
+
+	return ret;
+}
+
+static const struct clk_ops clk_spmi_pmic_div_ops = {
+	.enable = clk_spmi_pmic_div_enable,
+	.disable = clk_spmi_pmic_div_disable,
+	.set_rate = clk_spmi_pmic_div_set_rate,
+	.recalc_rate = clk_spmi_pmic_div_recalc_rate,
+	.round_rate = clk_spmi_pmic_div_round_rate,
+};
+
+struct spmi_pmic_div_clk_cc {
+	int		nclks;
+	struct clkdiv	clks[];
+};
+
+static struct clk_hw *
+spmi_pmic_div_clk_hw_get(struct of_phandle_args *clkspec, void *data)
+{
+	struct spmi_pmic_div_clk_cc *cc = data;
+	int idx = clkspec->args[0] - 1; /* Start at 1 instead of 0 */
+
+	if (idx < 0 || idx >= cc->nclks) {
+		pr_err("%s: index value %u is invalid; allowed range [1, %d]\n",
+		       __func__, clkspec->args[0], cc->nclks);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return &cc->clks[idx].hw;
+}
+
+static int spmi_pmic_clkdiv_probe(struct platform_device *pdev)
+{
+	struct spmi_pmic_div_clk_cc *cc;
+	struct clk_init_data init = {};
+	struct clkdiv *clkdiv;
+	struct clk *cxo;
+	struct regmap *regmap;
+	struct device *dev = &pdev->dev;
+	struct device_node *of_node = dev->of_node;
+	const char *parent_name;
+	int nclks, i, ret, cxo_hz;
+	char name[20];
+	u32 start;
+
+	ret = of_property_read_u32(of_node, "reg", &start);
+	if (ret < 0) {
+		dev_err(dev, "reg property reading failed\n");
+		return ret;
+	}
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap) {
+		dev_err(dev, "Couldn't get parent's regmap\n");
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32(of_node, "qcom,num-clkdivs", &nclks);
+	if (ret < 0) {
+		dev_err(dev, "qcom,num-clkdivs property reading failed, ret=%d\n",
+			ret);
+		return ret;
+	}
+
+	if (!nclks)
+		return -EINVAL;
+
+	cc = devm_kzalloc(dev, sizeof(*cc) + sizeof(*cc->clks) * nclks,
+			  GFP_KERNEL);
+	if (!cc)
+		return -ENOMEM;
+	cc->nclks = nclks;
+
+	cxo = clk_get(dev, "xo");
+	if (IS_ERR(cxo)) {
+		ret = PTR_ERR(cxo);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "failed to get xo clock\n");
+		return ret;
+	}
+	cxo_hz = clk_get_rate(cxo);
+	clk_put(cxo);
+
+	parent_name = of_clk_get_parent_name(of_node, 0);
+	if (!parent_name) {
+		dev_err(dev, "missing parent clock\n");
+		return -ENODEV;
+	}
+
+	init.name = name;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+	init.ops = &clk_spmi_pmic_div_ops;
+
+	for (i = 0, clkdiv = cc->clks; i < nclks; i++) {
+		snprintf(name, sizeof(name), "div_clk%d", i + 1);
+
+		spin_lock_init(&clkdiv[i].lock);
+		clkdiv[i].base = start + i * 0x100;
+		clkdiv[i].regmap = regmap;
+		clkdiv[i].cxo_period_ns = NSEC_PER_SEC / cxo_hz;
+		clkdiv[i].hw.init = &init;
+
+		ret = devm_clk_hw_register(dev, &clkdiv[i].hw);
+		if (ret)
+			return ret;
+	}
+
+	return devm_of_clk_add_hw_provider(dev, spmi_pmic_div_clk_hw_get, cc);
+}
+
+static const struct of_device_id spmi_pmic_clkdiv_match_table[] = {
+	{ .compatible = "qcom,spmi-clkdiv" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, spmi_pmic_clkdiv_match_table);
+
+static struct platform_driver spmi_pmic_clkdiv_driver = {
+	.driver		= {
+		.name	= "qcom,spmi-pmic-clkdiv",
+		.of_match_table = spmi_pmic_clkdiv_match_table,
+	},
+	.probe		= spmi_pmic_clkdiv_probe,
+};
+module_platform_driver(spmi_pmic_clkdiv_driver);
+
+MODULE_DESCRIPTION("QCOM SPMI PMIC clkdiv driver");
+MODULE_LICENSE("GPL v2");