i2c: Add TPS6586X driver

This power management chip supports battery charging and a large number
of power supplies. This initial driver only provides the ability to adjust
the two synchronous buck converters SM0 and SM1 in a stepwise manner.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

drivers/power/Makefile

@@ -26,6 +26,7 @@ include $(TOPDIR)/config.mk
 LIB 	:= $(obj)libpower.o
 
 COBJS-$(CONFIG_FTPMU010_POWER)	+= ftpmu010.o
+COBJS-$(CONFIG_TPS6586X_POWER)	+= tps6586x.o
 COBJS-$(CONFIG_TWL4030_POWER)	+= twl4030.o
 COBJS-$(CONFIG_TWL6030_POWER)	+= twl6030.o
 COBJS-$(CONFIG_TWL6035_POWER)	+= twl6035.o

drivers/power/tps6586x.c

@@ -0,0 +1,280 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * (C) Copyright 2010,2011 NVIDIA Corporation <www.nvidia.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <tps6586x.h>
+#include <asm/io.h>
+#include <i2c.h>
+
+static int bus_num;		/* I2C bus we are on */
+#define I2C_ADDRESS		0x34	/* chip requires this address */
+static char inited;		/* 1 if we have been inited */
+
+enum {
+	/* Registers that we access */
+	SUPPLY_CONTROL1		= 0x20,
+	SUPPLY_CONTROL2,
+	SM1_VOLTAGE_V1		= 0x23,
+	SM1_VOLTAGE_V2,
+	SM0_VOLTAGE_V1		= 0x26,
+	SM0_VOLTAGE_V2,
+	PFM_MODE		= 0x47,
+
+	/* Bits in the supply control registers */
+	CTRL_SM1_RAMP		= 0x01,
+	CTRL_SM1_SUPPLY2	= 0x02,
+	CTRL_SM0_RAMP		= 0x04,
+	CTRL_SM0_SUPPLY2	= 0x08,
+};
+
+#define MAX_I2C_RETRY	3
+int tps6586x_read(int reg)
+{
+	int	i;
+	uchar	data;
+	int	retval = -1;
+	int	old_bus_num;
+
+	old_bus_num = i2c_get_bus_num();
+	i2c_set_bus_num(bus_num);
+
+	for (i = 0; i < MAX_I2C_RETRY; ++i) {
+		if (!i2c_read(I2C_ADDRESS, reg, 1, &data, 1)) {
+			retval = (int)data;
+			goto exit;
+		}
+
+		/* i2c access failed, retry */
+		udelay(100);
+	}
+
+exit:
+	i2c_set_bus_num(old_bus_num);
+	debug("pmu_read %x=%x\n", reg, retval);
+	if (retval < 0)
+		debug("%s: failed to read register %#x: %d\n", __func__, reg,
+		      retval);
+	return retval;
+}
+
+int tps6586x_write(int reg, uchar *data, uint len)
+{
+	int	i;
+	int	retval = -1;
+	int	old_bus_num;
+
+	old_bus_num = i2c_get_bus_num();
+	i2c_set_bus_num(bus_num);
+
+	for (i = 0; i < MAX_I2C_RETRY; ++i) {
+		if (!i2c_write(I2C_ADDRESS, reg, 1, data, len)) {
+			retval = 0;
+			goto exit;
+		}
+
+		/* i2c access failed, retry */
+		udelay(100);
+	}
+
+exit:
+	i2c_set_bus_num(old_bus_num);
+	debug("pmu_write %x=%x: ", reg, retval);
+	for (i = 0; i < len; i++)
+		debug("%x ", data[i]);
+	if (retval)
+		debug("%s: failed to write register %#x\n", __func__, reg);
+	return retval;
+}
+
+/*
+ * Get current voltage of SM0 and SM1
+ *
+ * @param sm0	Place to put SM0 voltage
+ * @param sm1	Place to put SM1 voltage
+ * @return 0 if ok, -1 on error
+ */
+static int read_voltages(int *sm0, int *sm1)
+{
+	int ctrl1, ctrl2;
+	int is_v2;
+
+	/*
+	 * Each vdd has two supply sources, ie, v1 and v2.
+	 * The supply control reg1 and reg2 determine the current selection.
+	 */
+	ctrl1 = tps6586x_read(SUPPLY_CONTROL1);
+	ctrl2 = tps6586x_read(SUPPLY_CONTROL2);
+	if (ctrl1 == -1 || ctrl2 == -1)
+		return -1;
+
+	/* Figure out whether V1 or V2 is selected */
+	is_v2 = (ctrl1 | ctrl2) & CTRL_SM0_SUPPLY2;
+	*sm0 = tps6586x_read(is_v2 ? SM0_VOLTAGE_V2 : SM0_VOLTAGE_V1);
+	*sm1 = tps6586x_read(is_v2 ? SM1_VOLTAGE_V2 : SM1_VOLTAGE_V1);
+	if (*sm0 == -1 || *sm1 == -1)
+		return -1;
+
+	return 0;
+}
+
+static int set_voltage(int reg, int data, int rate)
+{
+	uchar control_bit;
+	uchar buff[3];
+
+	control_bit = (reg == SM0_VOLTAGE_V1 ? CTRL_SM0_RAMP : CTRL_SM1_RAMP);
+
+	/*
+	 * Only one supply is needed in u-boot. set both v1 and v2 to
+	 * same value.
+	 *
+	 * When both v1 and v2 are set to same value, we just need to set
+	 * control1 reg to trigger the supply selection.
+	 */
+	buff[0] = buff[1] = (uchar)data;
+	buff[2] = rate;
+
+	/* write v1, v2 and rate, then trigger */
+	if (tps6586x_write(reg, buff, 3) ||
+	    tps6586x_write(SUPPLY_CONTROL1, &control_bit, 1))
+		return -1;
+
+	return 0;
+}
+
+static int calculate_next_voltage(int voltage, int target, int step)
+{
+	int diff = voltage < target ? step : -step;
+
+	if (abs(target - voltage) > step)
+		voltage += diff;
+	else
+		voltage = target;
+
+	return voltage;
+}
+
+int tps6586x_set_pwm_mode(int mask)
+{
+	uchar val;
+	int ret;
+
+	assert(inited);
+	ret = tps6586x_read(PFM_MODE);
+	if (ret != -1) {
+		val = (uchar)ret;
+		val |= mask;
+
+		ret = tps6586x_write(PFM_MODE, &val, 1);
+	}
+
+	if (ret == -1)
+		debug("%s: Failed to read/write PWM mode reg\n", __func__);
+
+	return ret;
+}
+
+int tps6586x_adjust_sm0_sm1(int sm0_target, int sm1_target, int step, int rate,
+			    int min_sm0_over_sm1)
+{
+	int sm0, sm1;
+	int bad;
+
+	assert(inited);
+
+	/* get current voltage settings */
+	if (read_voltages(&sm0, &sm1)) {
+		debug("%s: Cannot read voltage settings\n", __func__);
+		return -1;
+	}
+
+	/*
+	 * if vdd_core < vdd_cpu + rel
+	 *    skip
+	 *
+	 * This condition may happen when system reboots due to kernel crash.
+	 */
+	if (min_sm0_over_sm1 != -1 && sm0 < sm1 + min_sm0_over_sm1) {
+		debug("%s: SM0 is %d, SM1 is %d, but min_sm0_over_sm1 is %d\n",
+		      __func__, sm0, sm1, min_sm0_over_sm1);
+		return -1;
+	}
+
+	/*
+	 * Since vdd_core and vdd_cpu may both stand at either greater or less
+	 * than their nominal voltage, the adjustment may go either directions.
+	 *
+	 * Make sure vdd_core is always higher than vdd_cpu with certain margin.
+	 * So, find out which vdd to adjust first in each step.
+	 *
+	 * case 1: both sm0 and sm1 need to move up
+	 *              adjust sm0 before sm1
+	 *
+	 * case 2: both sm0 and sm1 need to move down
+	 *              adjust sm1 before sm0
+	 *
+	 * case 3: sm0 moves down and sm1 moves up
+	 *              adjusting either one first is fine.
+	 *
+	 * Adjust vdd_core and vdd_cpu one step at a time until they reach
+	 * their nominal values.
+	 */
+	bad = 0;
+	while (!bad && (sm0 != sm0_target || sm1 != sm1_target)) {
+		int adjust_sm0_late = 0; /* flag to adjust vdd_core later */
+
+		debug("%d-%d   %d-%d   ", sm0, sm0_target, sm1, sm1_target);
+
+		if (sm0 != sm0_target) {
+			/*
+			 * if case 1 and case 3, set new sm0 first.
+			 * otherwise, hold down until new sm1 is set.
+			 */
+			sm0 = calculate_next_voltage(sm0, sm0_target, step);
+			if (sm1 < sm1_target)
+				bad |= set_voltage(SM0_VOLTAGE_V1, sm0, rate);
+			else
+				adjust_sm0_late = 1;
+		}
+
+		if (sm1 != sm1_target) {
+			sm1 = calculate_next_voltage(sm1, sm1_target, step);
+			bad |= set_voltage(SM1_VOLTAGE_V1, sm1, rate);
+		}
+
+		if (adjust_sm0_late)
+			bad |= set_voltage(SM0_VOLTAGE_V1, sm0, rate);
+		debug("%d\n", adjust_sm0_late);
+	}
+	debug("%d-%d   %d-%d   done\n", sm0, sm0_target, sm1, sm1_target);
+
+	return bad ? -1 : 0;
+}
+
+int tps6586x_init(int bus)
+{
+	bus_num = bus;
+	inited = 1;
+
+	return 0;
+}

include/tps6586x.h

@@ -0,0 +1,68 @@
+/*
+ *  (C) Copyright 2010,2011
+ *  NVIDIA Corporation <www.nvidia.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __H_
+#define _TPS6586X_H_
+
+enum {
+	/* SM0-2 PWM/PFM Mode Selection */
+	TPS6586X_PWM_SM0	= 1 << 0,
+	TPS6586X_PWM_SM1	= 1 << 1,
+	TPS6586X_PWM_SM2	= 1 << 2,
+};
+
+/**
+ * Enable PWM mode for selected SM0-2
+ *
+ * @param mask	Mask of synchronous converter to enable (TPS6586X_PWM_...)
+ * @return 0 if ok, -1 on error
+ */
+int tps6586x_set_pwm_mode(int mask);
+
+/**
+ * Adjust SM0 and SM1 voltages to the given targets in incremental steps.
+ *
+ * @param sm0_target	Target voltage for SM0 in 25mW units, 0=725mV, 31=1.5V
+ * @param sm1_target	Target voltage for SM1 in 25mW units, 0=725mV, 31=1.5V
+ * @param step		Amount to change voltage in each step, in 25mW units
+ * @param rate		Slew ratein mV/us: 0=instantly, 1=0.11, 2=0.22,
+ *			3=0.44, 4=0.88, 5=1.76, 6=3.52, 7=7.04
+ * @param min_sm0_over_sm1	Minimum amount by which sm0 must exceed sm1.
+ *			If this condition is not met, no adjustment will be
+ *			done and an error will be reported. Use -1 to skip
+ *			this check.
+ * @return 0 if ok, -1 on error
+ */
+int tps6586x_adjust_sm0_sm1(int sm0_target, int sm1_target, int step, int rate,
+			    int min_sm0_over_sm1);
+
+/**
+ * Set up the TPS6586X I2C bus number. This will be used for all operations
+ * on the device. This function must be called before using other functions.
+ *
+ * @param bus	I2C bus number containing the TPS6586X chip
+ * @return 0 (always succeeds)
+ */
+int tps6586x_init(int bus);
+
+#endif	/* _TPS6586X_H_ */