CLK: TI: Driver for DRA7 ATL (Audio Tracking Logic)

Audio Tracking Logic is designed to be used by HD Radio applications to
synchronize the audio output clocks to the baseband clock. ATL can be also
used to track errors between two reference clocks (BWS, AWS) and generate a modulated
clock output which averages to some desired frequency.
In essence ATL is generating a clock to be used by an audio codec and also
to be used by the SoC as MCLK.

To be able to integrate the ATL provided clocks to the clock tree we need
two types of DT binding:
- DT clock nodes to represent the ATL clocks towards the CCF
- binding for the ATL IP itself which is going to handle the hw
  configuration

The reason for this type of setup is that ATL itself is a separate device
in the SoC, it has it's own address space and clock domain. Other IPs can
use the ATL generated clock as their functional clock (McASPs for example)
and external components like audio codecs can also use the very same clock
as their MCLK.

The ATL IP in DRA7 contains 4 ATL instences.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>

drivers/clk/ti/Makefile

@@ -7,6 +7,7 @@ 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)		+= $(clk-common) clk-44xx.o
 obj-$(CONFIG_SOC_OMAP5)			+= $(clk-common) clk-54xx.o
-obj-$(CONFIG_SOC_DRA7XX)		+= $(clk-common) clk-7xx.o
+obj-$(CONFIG_SOC_DRA7XX)		+= $(clk-common) clk-7xx.o \
+					   clk-dra7-atl.o
 obj-$(CONFIG_SOC_AM43XX)		+= $(clk-common) clk-43xx.o
 endif

drivers/clk/ti/clk-dra7-atl.c

+/*
+ * DRA7 ATL (Audio Tracking Logic) clock driver
+ *
+ * Copyright (C) 2013 Texas Instruments, Inc.
+ *
+ * Peter Ujfalusi <peter.ujfalusi@ti.com>
+ *
+ * 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 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/module.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#define DRA7_ATL_INSTANCES	4
+
+#define DRA7_ATL_PPMR_REG(id)		(0x200 + (id * 0x80))
+#define DRA7_ATL_BBSR_REG(id)		(0x204 + (id * 0x80))
+#define DRA7_ATL_ATLCR_REG(id)		(0x208 + (id * 0x80))
+#define DRA7_ATL_SWEN_REG(id)		(0x210 + (id * 0x80))
+#define DRA7_ATL_BWSMUX_REG(id)		(0x214 + (id * 0x80))
+#define DRA7_ATL_AWSMUX_REG(id)		(0x218 + (id * 0x80))
+#define DRA7_ATL_PCLKMUX_REG(id)	(0x21c + (id * 0x80))
+
+#define DRA7_ATL_SWEN			BIT(0)
+#define DRA7_ATL_DIVIDER_MASK		(0x1f)
+#define DRA7_ATL_PCLKMUX		BIT(0)
+struct dra7_atl_clock_info;
+
+struct dra7_atl_desc {
+	struct clk *clk;
+	struct clk_hw hw;
+	struct dra7_atl_clock_info *cinfo;
+	int id;
+
+	bool probed;		/* the driver for the IP has been loaded */
+	bool valid;		/* configured */
+	bool enabled;
+	u32 bws;		/* Baseband Word Select Mux */
+	u32 aws;		/* Audio Word Select Mux */
+	u32 divider;		/* Cached divider value */
+};
+
+struct dra7_atl_clock_info {
+	struct device *dev;
+	void __iomem *iobase;
+
+	struct dra7_atl_desc *cdesc;
+};
+
+#define to_atl_desc(_hw)	container_of(_hw, struct dra7_atl_desc, hw)
+
+static inline void atl_write(struct dra7_atl_clock_info *cinfo, u32 reg,
+			     u32 val)
+{
+	__raw_writel(val, cinfo->iobase + reg);
+}
+
+static inline int atl_read(struct dra7_atl_clock_info *cinfo, u32 reg)
+{
+	return __raw_readl(cinfo->iobase + reg);
+}
+
+static int atl_clk_enable(struct clk_hw *hw)
+{
+	struct dra7_atl_desc *cdesc = to_atl_desc(hw);
+
+	if (!cdesc->probed)
+		goto out;
+
+	if (unlikely(!cdesc->valid))
+		dev_warn(cdesc->cinfo->dev, "atl%d has not been configured\n",
+			 cdesc->id);
+	pm_runtime_get_sync(cdesc->cinfo->dev);
+
+	atl_write(cdesc->cinfo, DRA7_ATL_ATLCR_REG(cdesc->id),
+		  cdesc->divider - 1);
+	atl_write(cdesc->cinfo, DRA7_ATL_SWEN_REG(cdesc->id), DRA7_ATL_SWEN);
+
+out:
+	cdesc->enabled = true;
+
+	return 0;
+}
+
+static void atl_clk_disable(struct clk_hw *hw)
+{
+	struct dra7_atl_desc *cdesc = to_atl_desc(hw);
+
+	if (!cdesc->probed)
+		goto out;
+
+	atl_write(cdesc->cinfo, DRA7_ATL_SWEN_REG(cdesc->id), 0);
+	pm_runtime_put_sync(cdesc->cinfo->dev);
+
+out:
+	cdesc->enabled = false;
+}
+
+static int atl_clk_is_enabled(struct clk_hw *hw)
+{
+	struct dra7_atl_desc *cdesc = to_atl_desc(hw);
+
+	return cdesc->enabled;
+}
+
+static unsigned long atl_clk_recalc_rate(struct clk_hw *hw,
+					 unsigned long parent_rate)
+{
+	struct dra7_atl_desc *cdesc = to_atl_desc(hw);
+
+	return parent_rate / cdesc->divider;
+}
+
+static long atl_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long *parent_rate)
+{
+	unsigned divider;
+
+	divider = (*parent_rate + rate / 2) / rate;
+	if (divider > DRA7_ATL_DIVIDER_MASK + 1)
+		divider = DRA7_ATL_DIVIDER_MASK + 1;
+
+	return *parent_rate / divider;
+}
+
+static int atl_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			    unsigned long parent_rate)
+{
+	struct dra7_atl_desc *cdesc = to_atl_desc(hw);
+	u32 divider;
+
+	divider = ((parent_rate + rate / 2) / rate) - 1;
+	if (divider > DRA7_ATL_DIVIDER_MASK)
+		divider = DRA7_ATL_DIVIDER_MASK;
+
+	cdesc->divider = divider + 1;
+
+	return 0;
+}
+
+const struct clk_ops atl_clk_ops = {
+	.enable		= atl_clk_enable,
+	.disable	= atl_clk_disable,
+	.is_enabled	= atl_clk_is_enabled,
+	.recalc_rate	= atl_clk_recalc_rate,
+	.round_rate	= atl_clk_round_rate,
+	.set_rate	= atl_clk_set_rate,
+};
+
+static void __init of_dra7_atl_clock_setup(struct device_node *node)
+{
+	struct dra7_atl_desc *clk_hw = NULL;
+	struct clk_init_data init = { 0 };
+	const char **parent_names = NULL;
+	struct clk *clk;
+
+	clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL);
+	if (!clk_hw) {
+		pr_err("%s: could not allocate dra7_atl_desc\n", __func__);
+		return;
+	}
+
+	clk_hw->hw.init = &init;
+	clk_hw->divider = 1;
+	init.name = node->name;
+	init.ops = &atl_clk_ops;
+	init.flags = CLK_IGNORE_UNUSED;
+	init.num_parents = of_clk_get_parent_count(node);
+
+	if (init.num_parents != 1) {
+		pr_err("%s: atl clock %s must have 1 parent\n", __func__,
+		       node->name);
+		goto cleanup;
+	}
+
+	parent_names = kzalloc(sizeof(char *), GFP_KERNEL);
+
+	if (!parent_names)
+		goto cleanup;
+
+	parent_names[0] = of_clk_get_parent_name(node, 0);
+
+	init.parent_names = parent_names;
+
+	clk = clk_register(NULL, &clk_hw->hw);
+
+	if (!IS_ERR(clk)) {
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+		return;
+	}
+cleanup:
+	kfree(parent_names);
+	kfree(clk_hw);
+}
+CLK_OF_DECLARE(dra7_atl_clock, "ti,dra7-atl-clock", of_dra7_atl_clock_setup);
+
+static int of_dra7_atl_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct dra7_atl_clock_info *cinfo;
+	int i;
+	int ret = 0;
+
+	if (!node)
+		return -ENODEV;
+
+	cinfo = devm_kzalloc(&pdev->dev, sizeof(*cinfo), GFP_KERNEL);
+	if (!cinfo)
+		return -ENOMEM;
+
+	cinfo->iobase = of_iomap(node, 0);
+	cinfo->dev = &pdev->dev;
+	pm_runtime_enable(cinfo->dev);
+
+	pm_runtime_get_sync(cinfo->dev);
+	atl_write(cinfo, DRA7_ATL_PCLKMUX_REG(0), DRA7_ATL_PCLKMUX);
+
+	for (i = 0; i < DRA7_ATL_INSTANCES; i++) {
+		struct device_node *cfg_node;
+		char prop[5];
+		struct dra7_atl_desc *cdesc;
+		struct of_phandle_args clkspec;
+		struct clk *clk;
+		int rc;
+
+		rc = of_parse_phandle_with_args(node, "ti,provided-clocks",
+						NULL, i, &clkspec);
+
+		if (rc) {
+			pr_err("%s: failed to lookup atl clock %d\n", __func__,
+			       i);
+			return -EINVAL;
+		}
+
+		clk = of_clk_get_from_provider(&clkspec);
+
+		cdesc = to_atl_desc(__clk_get_hw(clk));
+		cdesc->cinfo = cinfo;
+		cdesc->id = i;
+
+		/* Get configuration for the ATL instances */
+		snprintf(prop, sizeof(prop), "atl%u", i);
+		cfg_node = of_find_node_by_name(node, prop);
+		if (cfg_node) {
+			ret = of_property_read_u32(cfg_node, "bws",
+						   &cdesc->bws);
+			ret |= of_property_read_u32(cfg_node, "aws",
+						    &cdesc->aws);
+			if (!ret) {
+				cdesc->valid = true;
+				atl_write(cinfo, DRA7_ATL_BWSMUX_REG(i),
+					  cdesc->bws);
+				atl_write(cinfo, DRA7_ATL_AWSMUX_REG(i),
+					  cdesc->aws);
+			}
+		}
+
+		cdesc->probed = true;
+		/*
+		 * Enable the clock if it has been asked prior to loading the
+		 * hw driver
+		 */
+		if (cdesc->enabled)
+			atl_clk_enable(__clk_get_hw(clk));
+	}
+	pm_runtime_put_sync(cinfo->dev);
+
+	return ret;
+}
+
+static int of_dra7_atl_clk_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static struct of_device_id of_dra7_atl_clk_match_tbl[] = {
+	{ .compatible = "ti,dra7-atl", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_dra7_atl_clk_match_tbl);
+
+static struct platform_driver dra7_atl_clk_driver = {
+	.driver = {
+		.name = "dra7-atl",
+		.owner = THIS_MODULE,
+		.of_match_table = of_dra7_atl_clk_match_tbl,
+	},
+	.probe = of_dra7_atl_clk_probe,
+	.remove = of_dra7_atl_clk_remove,
+};
+
+module_platform_driver(dra7_atl_clk_driver);
+
+MODULE_DESCRIPTION("Clock driver for DRA7 Audio Tracking Logic");
+MODULE_ALIAS("platform:dra7-atl-clock");
+MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@ti.com>");
+MODULE_LICENSE("GPL v2");