[RFC PATCH 5/6] PM / Voltagedomain: introduce basic voltage domain support for OMAP

[Nishanth Menon]

OMAP platforms have multiple voltage domains, but each with consistent
behavior of controlling the VDD (supply) and VBB(ABB/Bias voltage).

These need to be sequenced in a specific order for functionality.
Further optimization such as AVS(Adaptive Voltage Scaling), optimized
voltages from efuse(Class0) can also be introduced based on this basic
framework.

This now allows reuse by voltage domain devices which may share the same
voltage domain by allowing the regulator framework to maintain per
consumer usage information.

Signed-off-by: Nishanth Menon <nm@xxxxxx>
---
 drivers/power/voltdm/Kconfig       |    7 +
 drivers/power/voltdm/Makefile      |    1 +
 drivers/power/voltdm/voltdm_omap.c |  287 ++++++++++++++++++++++++++++++++++++
 3 files changed, 295 insertions(+)
 create mode 100644 drivers/power/voltdm/voltdm_omap.c

diff --git a/drivers/power/voltdm/Kconfig b/drivers/power/voltdm/Kconfig
index 270fdab..41bfbc3 100644
--- a/drivers/power/voltdm/Kconfig
+++ b/drivers/power/voltdm/Kconfig
@@ -9,4 +9,11 @@ config VOLTAGE_DOMAIN
 menu "Voltage Domain Framework Drivers"
 	depends on VOLTAGE_DOMAIN
 
+config VOLTAGE_DOMAIN_OMAP
+	tristate "TI OMAP Voltage domain driver"
+	---help---
+	  Voltage domain support for OMAP platforms which need
+	  vdd regulator and Adaptive Body Bias(ABB) regulator
+	  support
+
 endmenu
diff --git a/drivers/power/voltdm/Makefile b/drivers/power/voltdm/Makefile
index fd32040..e1cb50d 100644
--- a/drivers/power/voltdm/Makefile
+++ b/drivers/power/voltdm/Makefile
@@ -3,3 +3,4 @@ obj-$(CONFIG_VOLTAGE_DOMAIN)	+= core.o
 
 # Hardware specific voltage domain
 # please keep this section sorted lexicographically by file/directory path name
+obj-$(CONFIG_VOLTAGE_DOMAIN_OMAP)	+= voltdm_omap.o
diff --git a/drivers/power/voltdm/voltdm_omap.c b/drivers/power/voltdm/voltdm_omap.c
new file mode 100644
index 0000000..aacbdde
--- /dev/null
+++ b/drivers/power/voltdm/voltdm_omap.c
@@ -0,0 +1,287 @@
+/*
+ * Copyright (C) 2014 Texas Instruments Incorporated - http://www.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.
+ *
+ * Helper functions for registering clock rate-change notifier handlers
+ * that scale voltage when a clock changes its output frequency.
+ */
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include "voltage_domain_private.h"
+
+/**
+ * struct omap_voltdm_data - OMAP specific voltage domain data
+ * @vdd_reg:	VDD regulator
+ * @vbb_reg:	Body Bias regulator
+ */
+struct omap_voltdm_data {
+	struct regulator *vdd_reg;
+	struct regulator *vbb_reg;
+};
+
+/**
+ * omap_voltdm_do_transition() - do the voltage domain transition
+ * @dev:	voltage domain device for which we are doing the transition
+ * @voltdm_data:	data specific to the device
+ * @clk_notifier_flags:	clk notifier flags for direction of transition
+ * @uv:		what voltage to transition to
+ * @tol_uv:	voltage tolerance to use
+ */
+static int omap_voltdm_do_transition(struct device *dev,
+				     void *voltdm_data,
+				     unsigned long clk_notifier_flags, int uv,
+				     int tol_uv)
+{
+	struct omap_voltdm_data *data = (struct omap_voltdm_data *)voltdm_data;
+	int ret;
+	bool do_abb_first;
+
+	/* We dont expect voltdm layer to make mistakes.. but still */
+	BUG_ON(!data);
+
+	do_abb_first = clk_notifier_flags == ABORT_RATE_CHANGE ||
+	    clk_notifier_flags == POST_RATE_CHANGE;
+
+	if (do_abb_first) {
+		dev_dbg(dev, "vbb pre %duV[tol %duV]\n", uv, tol_uv);
+		ret = regulator_set_voltage_tol(data->vbb_reg, uv, tol_uv);
+		if (ret) {
+			dev_err(dev,
+				"vbb failed for voltage %duV[tol %duV]:%d\n",
+				uv, tol_uv, ret);
+			return ret;
+		}
+	}
+
+	dev_dbg(dev, "vdd for voltage %duV[tol %duV]\n", uv, tol_uv);
+	ret = regulator_set_voltage_tol(data->vdd_reg, uv, tol_uv);
+	if (ret) {
+		dev_err(dev,
+			"vdd failed for voltage %duV[tol %duV]:%d\n",
+			uv, tol_uv, ret);
+		return ret;
+	}
+
+	if (!do_abb_first) {
+		dev_dbg(dev, "vbb post %duV[tol %duV]\n", uv, tol_uv);
+		ret = regulator_set_voltage_tol(data->vbb_reg, uv, tol_uv);
+		if (ret) {
+			dev_err(dev,
+				"vbb failed for voltage %duV[tol %duV]:%d\n",
+				uv, tol_uv, ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * omap_voltdm_latency() - provide the transition latency for the voltage domain
+ * @dev:	voltage domain device for which we are doing the transition
+ * @voltdm_data: data specific to the device
+ * @min:	minimum voltage in uV
+ * @max:	maximum voltage in uV
+ *
+ * Return: If successful, the combined transition latency from min to max, else
+ * returns error value
+ */
+static int omap_voltdm_latency(struct device *dev, void *voltdm_data,
+			       unsigned long min, unsigned long max)
+{
+	struct omap_voltdm_data *data = (struct omap_voltdm_data *)voltdm_data;
+	int ret, tot_latency = 0;
+
+	/* We dont expect voltdm layer to make mistakes.. but still */
+	BUG_ON(!data);
+
+	ret = regulator_set_voltage_time(data->vdd_reg, min, max);
+	if (ret < 0) {
+		dev_warn(dev, "vdd failed voltage latency: %d\n", ret);
+		return ret;
+	}
+	tot_latency += ret;
+
+	ret = regulator_set_voltage_time(data->vbb_reg, min, max);
+	if (ret < 0) {
+		dev_warn(dev, "vbb failed voltage latency: %d\n", ret);
+		return ret;
+	}
+	tot_latency += ret;
+
+	return tot_latency;
+}
+
+static inline void omap_voltdm_cleanup(struct omap_voltdm_data *data)
+{
+	if (!IS_ERR(data->vbb_reg))
+		regulator_put(data->vbb_reg);
+	if (!IS_ERR(data->vdd_reg))
+		regulator_put(data->vdd_reg);
+	kfree(data);
+}
+
+/**
+ * omap_voltdm_get() - get the voltage domain resources specific to request
+ * @voltdm_dev:	voltage domain device
+ * @request_dev:	device for which we have been requested to get
+ * @np:			unused
+ * @np_args:		unused
+ * @supply:		unused
+ * @*voltdm_data:	returns data for the current request (freed in put)
+ *
+ * Return: 0 if everything went OK, else return appropriate error value.
+ */
+static int omap_voltdm_get(struct device *voltdm_dev,
+			  struct device *request_dev,
+			  struct device_node *np,
+			  struct of_phandle_args *np_args,
+			  const char *supply,
+			  void **voltdm_data)
+{
+	struct omap_voltdm_data *data;
+	int ret = 0;
+
+	BUG_ON(!voltdm_dev || !request_dev || !voltdm_data);
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	/* Intialize for use in generic cleanup routine */
+	data->vdd_reg = ERR_PTR(-ENODEV);
+	data->vbb_reg = ERR_PTR(-ENODEV);
+
+	/*
+	 * Setup aliases for request device supply to let regulator framework
+	 * do multi-consumer scenario
+	 */
+	ret = regulator_register_supply_alias(request_dev, "vdd", voltdm_dev, "vdd");
+	if (ret)
+		goto out_free;
+	ret = regulator_register_supply_alias(request_dev, "vbb", voltdm_dev, "vbb");
+	if (ret)
+		goto out_unreg_vdd;
+
+	data->vdd_reg = regulator_get(request_dev, "vdd");
+	if (IS_ERR(data->vdd_reg)) {
+		ret = PTR_ERR(data->vdd_reg);
+		dev_err(voltdm_dev, "Unable to get vdd regulator:%d\n", ret);
+		goto out_unreg;
+	}
+
+	data->vbb_reg = regulator_get(request_dev, "vbb");
+	if (IS_ERR(data->vbb_reg)) {
+		ret = PTR_ERR(data->vbb_reg);
+		dev_err(voltdm_dev, "Unable to get vbb regulator:%d\n", ret);
+		goto out_vdd_reg;
+	}
+
+	*voltdm_data = data;
+	return 0;
+
+out_vdd_reg:
+	regulator_put(data->vdd_reg);
+out_unreg:
+	regulator_unregister_supply_alias(request_dev, "vbb");
+out_unreg_vdd:
+	regulator_unregister_supply_alias(request_dev, "vdd");
+out_free:
+	kfree(data);
+
+	return ret;
+}
+
+/**
+ * omap_voltdm_put() - release the resources reserved by omap_voltdm_get()
+ * @voltdm_dev:		voltage domain device for which we reserved resources
+ * @request_dev:	device for which we have been requested to put
+ * @voltdm_data:	data for the request provided by omap_voltdm_get()
+ */
+static void omap_voltdm_put(struct device *voltdm_dev, struct device *request_dev,
+			    void *voltdm_data)
+{
+	struct omap_voltdm_data *data = (struct omap_voltdm_data *)voltdm_data;
+
+	/* We dont expect voltdm layer to make mistakes.. but still */
+	BUG_ON(!data || !voltdm_dev || !request_dev);
+
+	regulator_put(data->vbb_reg);
+	regulator_put(data->vdd_reg);
+	regulator_unregister_supply_alias(request_dev, "vbb");
+	regulator_unregister_supply_alias(request_dev, "vdd");
+	kfree(data);
+
+	return;
+}
+
+static const struct pm_voltdm_ops omap_voltdm_ops = {
+	.voltdm_get = omap_voltdm_get,
+	.voltdm_put = omap_voltdm_put,
+	.voltdm_latency = omap_voltdm_latency,
+	.voltdm_do_transition = omap_voltdm_do_transition,
+};
+
+static const struct pm_voltdm_desc omap_voltdm_desc = {
+	.ops = &omap_voltdm_ops,
+};
+
+static const struct of_device_id omap_voltdm_of_match[] = {
+	{.compatible = "ti,omap-voltdm", .data = &omap_voltdm_desc},
+	{},
+};
+
+static int omap_voltdm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *match;
+	struct pm_voltdm_dev *vdev;
+	int ret = 0;
+
+	match = of_match_device(omap_voltdm_of_match, dev);
+	if (!match) {
+		/* We do not expect this to happen */
+		dev_err(dev, "%s: Unable to match device\n", __func__);
+		return -ENODEV;
+	}
+	if (!match->data) {
+		/* Again, unlikely.. but mistakes do happen */
+		dev_err(dev, "%s: Bad data in match\n", __func__);
+		return -EINVAL;
+	}
+
+	vdev = devm_voltdm_register(dev, match->data);
+	if (IS_ERR(vdev)) {
+		ret = PTR_ERR(vdev);
+		dev_err(dev, "Failed to register voltage domain %d\n", ret);
+	}
+
+	return ret;
+}
+
+MODULE_ALIAS("platform:omap_voltdm");
+
+static struct platform_driver omap_voltdm_driver = {
+	.probe = omap_voltdm_probe,
+	.driver = {
+		   .name = "omap_voltdm",
+		   .owner = THIS_MODULE,
+		   .of_match_table = of_match_ptr(omap_voltdm_of_match),
+		   },
+};
+module_platform_driver(omap_voltdm_driver);
+
+MODULE_DESCRIPTION("Texas Instruments OMAP Voltage Domain driver");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

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