dm: power: Add support for TPS65090 FETs

The TPS65090 has 7 FETs which are modelled as regulators. This allows them
to be controlled by drivers easier, accessed through the 'regulator' command
and used by other drivers.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>

drivers/power/regulator/Kconfig

@@ -61,3 +61,13 @@ config DM_REGULATOR_SANDBOX
 
 	A detailed information can be found in header: '<power/sandbox_pmic.h>'
 	Binding info: 'doc/device-tree-bindings/pmic/max77686.txt'
+
+config REGULATOR_TPS65090
+	bool "Enable driver for TPS65090 PMIC regulators"
+	depends on PMIC_TPS65090
+	---help---
+	The TPS65090 provides several FETs (Field-effect Transistors,
+	effectively switches) which are supported by this driver as
+	regulators, one for each FET. The standard regulator interface is
+	supported, but it is only possible to turn the regulators on or off.
+	There is no voltage/current control.

drivers/power/regulator/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_DM_REGULATOR) += regulator-uclass.o
 obj-$(CONFIG_DM_REGULATOR_MAX77686) += max77686.o
 obj-$(CONFIG_DM_REGULATOR_FIXED) += fixed.o
 obj-$(CONFIG_DM_REGULATOR_SANDBOX) += sandbox.o
+obj-$(CONFIG_REGULATOR_TPS65090) += tps65090_regulator.o

drivers/power/regulator/tps65090_regulator.c

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <power/pmic.h>
+#include <power/regulator.h>
+#include <power/tps65090.h>
+
+static int tps65090_fet_probe(struct udevice *dev)
+{
+	struct dm_regulator_uclass_platdata *uc_pdata;
+
+	uc_pdata = dev_get_uclass_platdata(dev);
+
+	uc_pdata->type = REGULATOR_TYPE_OTHER;
+	uc_pdata->mode_count = 0;
+
+	return 0;
+}
+
+static bool tps65090_fet_get_enable(struct udevice *dev)
+{
+	struct udevice *pmic = dev_get_parent(dev);
+	int ret, fet_id;
+
+	fet_id = dev->driver_data;
+	debug("%s: fet_id=%d\n", __func__, fet_id);
+
+	ret = pmic_reg_read(pmic, REG_FET_BASE + fet_id);
+	if (ret < 0)
+		return ret;
+
+	return ret & FET_CTRL_ENFET;
+}
+
+/**
+ * Set the power state for a FET
+ *
+ * @param pmic		pmic structure for the tps65090
+ * @param fet_id	FET number to set (1..MAX_FET_NUM)
+ * @param set		1 to power on FET, 0 to power off
+ * @return -EIO if we got a comms error, -EAGAIN if the FET failed to
+ * change state. If all is ok, returns 0.
+ */
+static int tps65090_fet_set(struct udevice *pmic, int fet_id, bool set)
+{
+	int retry;
+	u32 value;
+	int ret;
+
+	value = FET_CTRL_ADENFET | FET_CTRL_WAIT;
+	if (set)
+		value |= FET_CTRL_ENFET;
+
+	if (pmic_reg_write(pmic, REG_FET_BASE + fet_id, value))
+		return -EIO;
+
+	/* Try reading until we get a result */
+	for (retry = 0; retry < MAX_CTRL_READ_TRIES; retry++) {
+		ret = pmic_reg_read(pmic, REG_FET_BASE + fet_id);
+		if (ret < 0)
+			return ret;
+
+		/* Check that the FET went into the expected state */
+		debug("%s: flags=%x\n", __func__, ret);
+		if (!!(ret & FET_CTRL_PGFET) == set)
+			return 0;
+
+		/* If we got a timeout, there is no point in waiting longer */
+		if (ret & FET_CTRL_TOFET)
+			break;
+
+		mdelay(1);
+	}
+
+	debug("FET %d: Power good should have set to %d but reg=%#02x\n",
+	      fet_id, set, ret);
+	return -EAGAIN;
+}
+
+static int tps65090_fet_set_enable(struct udevice *dev, bool enable)
+{
+	struct udevice *pmic = dev_get_parent(dev);
+	int ret, fet_id;
+	ulong start;
+	int loops;
+
+	fet_id = dev->driver_data;
+	debug("%s: fet_id=%d, enable=%d\n", __func__, fet_id, enable);
+
+	start = get_timer(0);
+	for (loops = 0;; loops++) {
+		ret = tps65090_fet_set(pmic, fet_id, enable);
+		if (!ret)
+			break;
+
+		if (get_timer(start) > 100)
+			break;
+
+		/* Turn it off and try again until we time out */
+		tps65090_fet_set(pmic, fet_id, false);
+	}
+
+	if (ret)
+		debug("%s: FET%d failed to power on: time=%lums, loops=%d\n",
+		      __func__, fet_id, get_timer(start), loops);
+	else if (loops)
+		debug("%s: FET%d powered on after %lums, loops=%d\n",
+		      __func__, fet_id, get_timer(start), loops);
+
+	/*
+	 * Unfortunately there are some conditions where the power-good bit
+	 * will be 0, but the FET still comes up. One such case occurs with
+	 * the LCD backlight on snow. We'll just return 0 here and assume
+	 * that the FET will eventually come up.
+	 */
+	if (ret == -EAGAIN)
+		ret = 0;
+
+	return ret;
+}
+
+static const struct dm_regulator_ops tps65090_fet_ops = {
+	.get_enable = tps65090_fet_get_enable,
+	.set_enable = tps65090_fet_set_enable,
+};
+
+U_BOOT_DRIVER(tps65090_fet) = {
+	.name = TPS65090_FET_DRIVER,
+	.id = UCLASS_REGULATOR,
+	.ops = &tps65090_fet_ops,
+	.probe = tps65090_fet_probe,
+};