Add support for 1-wire protocol and power adapter LEDs

BUG=chrome-os-partner:7498
TEST=powerled {off, red, yellow, green}

Signed-off-by: Randall Spangler <rspangler@chromium.org>

Change-Id: I48beaad94d75c0ec30a969ea4b0e35f54e052085

board/link/board.c

@@ -30,7 +30,6 @@ const struct gpio_info gpio_list[GPIO_COUNT] = {
 	{"LID_SWITCHn",         LM4_GPIO_K, (1<<5), GPIO_INT_BOTH,
 	 power_button_interrupt},
 	/* Other inputs */
-	{"POWER_ONEWIRE",       LM4_GPIO_H, (1<<2), 0, NULL},
 	{"THERMAL_DATA_READYn", LM4_GPIO_B, (1<<4), 0, NULL},
 	{"AC_PRESENT",          LM4_GPIO_H, (1<<3), 0, NULL},
 	{"PCH_BKLTEN",          LM4_GPIO_J, (1<<3), GPIO_INT_BOTH,

board/link/board.h

@@ -9,9 +9,11 @@
 #define __BOARD_H
 
 /* Optional features */
+#define CONFIG_ONEWIRE
 #define CONFIG_PECI
-#define CONFIG_TMP006
+#define CONFIG_POWER_LED
 #define CONFIG_PSTORE
+#define CONFIG_TMP006
 
 /* 66.667 Mhz clock frequency */
 #define CPU_CLOCK  66666667
@@ -110,7 +112,6 @@ enum gpio_signal {
 	/* Inputs with interrupt handlers are first for efficiency */
 	GPIO_POWER_BUTTONn = 0,   /* Power button */
 	GPIO_LID_SWITCHn,         /* Lid switch */
-	GPIO_POWER_ONEWIRE,       /* 1-wire interface to power adapter LEDs */
 	GPIO_THERMAL_DATA_READYn, /* Data ready from I2C thermal sensor */
 	/* Other inputs */
 	GPIO_AC_PRESENT,          /* AC power present */

chip/lm4/build.mk

@@ -13,6 +13,7 @@ chip-y+=clock.o gpio.o system.o uart.o
 chip-y+=watchdog.o eeprom.o hwtimer.o
 chip-$(CONFIG_FLASH)+=flash.o
 chip-$(CONFIG_LPC)+=lpc.o
+chip-$(CONFIG_ONEWIRE)+=onewire.o
 chip-$(CONFIG_PECI)+=peci.o
 chip-$(CONFIG_PWM)+=pwm.o
 chip-$(CONFIG_TEMP_SENSOR)+=chip_temp_sensor.o

chip/lm4/onewire.c

@@ -0,0 +1,140 @@
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* 1-wire interface module for Chrome EC */
+
+#include "board.h"
+#include "gpio.h"
+#include "timer.h"
+#include "registers.h"
+
+#define ONEWIRE_PIN (1<<2)  /* One-wire pin mask (on GPIO H) */
+
+/* Standard speed; all timings padded by 2 usec for safety.
+ *
+ * Note that these timing are actually _longer_ than legacy 1-wire standard
+ * speed because we're running the 1-wire bus at 3.3V instead of 5V. */
+#define T_RSTL 602  /* Reset low pulse; 600-960 us */
+#define T_MSP   72  /* Presence detect sample time; 70-75 us */
+#define T_RSTH (68 + 260 + 5 + 2) /* Reset high; tPDHmax + tPDLmax + tRECmin */
+#define T_SLOT  70  /* Timeslot; >67 us */
+#define T_W0L   63  /* Write 0 low; 62-120 us */
+#define T_W1L    7  /* Write 1 low; 5-15 us */
+#define T_RL     7  /* Read low; 5-15 us */
+#define T_MSR    9  /* Read sample time; <15 us.  Must be at least 200 ns after
+		     * T_RL since that's how long the signal takes to be pulled
+		     * up on our board.  */
+
+
+/* Output low on the bus for <usec> us, then switch back to open-drain input */
+static void output0(int usec)
+{
+	LM4_GPIO_DIR(LM4_GPIO_H) |= ONEWIRE_PIN;
+	LM4_GPIO_DATA(LM4_GPIO_H, ONEWIRE_PIN) = 0;
+	udelay(usec);
+	LM4_GPIO_DIR(LM4_GPIO_H) &= ~ONEWIRE_PIN;
+}
+
+
+/* Read the signal line */
+static int readline(void)
+{
+	return LM4_GPIO_DATA(LM4_GPIO_H, ONEWIRE_PIN) ? 1 : 0;
+}
+
+
+/* Read a bit */
+static int readbit(void)
+{
+	int bit;
+
+	/* Output low */
+	output0(T_RL);
+
+	/* Delay to let slave release the line if it wants to send a 1-bit */
+	udelay(T_MSR - T_RL);
+
+	/* Read bit */
+	bit = readline();
+
+	/* Delay to end of timeslot */
+	udelay(T_SLOT - T_MSR);
+	return bit;
+}
+
+
+/* Write a bit */
+static void writebit(int bit)
+{
+	if (bit) {
+		output0(T_W1L);
+		udelay(T_SLOT - T_W1L);
+	} else {
+		output0(T_W0L);
+		udelay(T_SLOT - T_W0L);
+	}
+}
+
+
+int onewire_reset(void)
+{
+	/* Start transaction with master reset pulse */
+	output0(T_RSTL);
+
+	/* Wait for presence detect sample time */
+	udelay(T_MSP);
+	/* Alternately, we could poll waiting for a 1-bit indicating our pulse
+	 * has let go, then poll up to max time waiting for a 0-bit indicating
+	 * the slave has responded. */
+	if (readline() != 0)
+		return EC_ERROR_UNKNOWN;
+
+	/* Wait for end of presence pulse */
+	/* Alternately, we could poll waiting for a 1-bit */
+	udelay(T_RSTH - T_MSP);
+
+	return EC_SUCCESS;
+}
+
+
+int onewire_read(void)
+{
+	int data = 0;
+	int i;
+
+	for (i = 0; i < 8; i++)
+		data |= readbit() << i;  /* LSB first */
+
+	return data;
+}
+
+
+void onewire_write(int data)
+{
+	int i;
+
+	for (i = 0; i < 8; i++)
+		writebit((data >> i) & 0x01);  /* LSB first */
+}
+
+/*****************************************************************************/
+/* Initialization */
+
+/* Configures GPIOs for the module. */
+static void configure_gpio(void)
+{
+	/* Configure 1-wire pin as open-drain GPIO */
+	gpio_set_alternate_function(LM4_GPIO_H, ONEWIRE_PIN, 0);
+	LM4_GPIO_ODR(LM4_GPIO_H) |= ONEWIRE_PIN;
+}
+
+
+int onewire_init(void)
+{
+	/* Configure GPIOs */
+	configure_gpio();
+
+	return EC_SUCCESS;
+}

common/build.mk

@@ -20,6 +20,7 @@ common-$(CONFIG_TASK_THERMAL)+=thermal.o thermal_commands.o
 common-$(CONFIG_TEMP_SENSOR)+=temp_sensor.o temp_sensor_commands.o
 common-$(CONFIG_TMP006)+=tmp006.o
 common-$(CONFIG_LIGHTBAR)+=leds.o
+common-$(CONFIG_POWER_LED)+=power_led.o
 
 # Board driver modules
 common-$(CONFIG_CHARGER_BQ24725)+=charger_bq24725.o

common/main.c

@@ -20,6 +20,7 @@
 #include "keyboard_scan.h"
 #include "lpc.h"
 #include "memory_commands.h"
+#include "onewire.h"
 #include "peci.h"
 #include "port80.h"
 #include "power_button.h"
@@ -93,6 +94,9 @@ int main(void)
 #endif
 	adc_init();
 	usb_charge_init();
+#ifdef CONFIG_ONEWIRE
+	onewire_init();
+#endif
 #ifdef CONFIG_CHARGER
 	charger_init();
 #endif

common/power_led.c

@@ -0,0 +1,100 @@
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Power LED control for Chrome EC */
+
+#include "console.h"
+#include "onewire.h"
+#include "power_led.h"
+#include "timer.h"
+#include "uart.h"
+#include "util.h"
+
+#define POWERLED_RETRIES 10
+
+static const uint8_t led_masks[POWERLED_COLOR_COUNT] = {0xff, 0xfe, 0xfc, 0xfd};
+static const char * const color_names[POWERLED_COLOR_COUNT] = {
+	"off", "red", "yellow", "green"};
+
+
+/* Set the power LED GPIO controller outputs to the specified mask. */
+static int powerled_set_mask(int mask)
+{
+	int rv;
+
+	/* Reset the 1-wire bus */
+	rv = onewire_reset();
+	if (rv)
+		return rv;
+
+	/* Skip ROM, since only one device */
+	onewire_write(0xcc);
+
+	/* Write and turn on the LEDs */
+	onewire_write(0x5a);
+	onewire_write(mask);
+	onewire_write(~mask);  /* Repeat inverted */
+
+	rv = onewire_read();   /* Confirmation byte */
+	if (rv != 0xaa)
+		return EC_ERROR_UNKNOWN;
+
+	/* The next byte is a read-back of the chip status.  Since we're only
+	 * using lines as outputs, we can ignore it. */
+	return EC_SUCCESS;
+}
+
+
+int powerled_set(enum powerled_color color)
+{
+	int rv = EC_SUCCESS;
+	int i;
+
+	/* 1-wire communication can fail for timing reasons in the current
+	 * system.  We have a limited timing window to send/receive bits, but
+	 * we can't disable interrupts for the rest of the system to guarantee
+	 * we hit that window.  Instead, simply retry the low-level command a
+	 * few times. */
+	for (i = 0; i < POWERLED_RETRIES; i++) {
+		rv = powerled_set_mask(led_masks[color]);
+		if (rv == EC_SUCCESS)
+			break;
+
+		/* Sleep for a bit between tries.  This gives the 1-wire GPIO
+		 * chip time to recover from the failed attempt, and allows
+		 * lower-priority tasks a chance to run. */
+		usleep(100);
+	}
+
+	return rv;
+}
+
+
+/*****************************************************************************/
+/* Console commands */
+
+static int command_powerled(int argc, char **argv)
+{
+	int i = POWERLED_COLOR_COUNT;
+
+	/* Pick a color, any color... */
+	if (argc >= 1) {
+		for (i = 0; i < POWERLED_COLOR_COUNT; i++) {
+			if (!strcasecmp(argv[1], color_names[i]))
+				break;
+		}
+	}
+	if (i >= POWERLED_COLOR_COUNT) {
+		uart_puts("Please specify a color:");
+		for (i = 0; i < POWERLED_COLOR_COUNT; i++)
+			uart_printf(" %s", color_names[i]);
+		uart_puts("\n");
+		return EC_ERROR_INVAL;
+	}
+
+	uart_printf("Setting power LED to %s...\n", color_names[i]);
+	return powerled_set(i);
+}
+DECLARE_CONSOLE_COMMAND(powerled, command_powerled);

include/onewire.h

@@ -0,0 +1,32 @@
+/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* 1-wire interface for Chrome EC */
+
+/* Note that 1-wire communication is VERY latency-sensitive.  If these
+ * functions are run at low priority, communication may be garbled.  However,
+ * these functions are also slow enough (~1ms per call) that it's really not
+ * desirable to put them at high priority.  So make sure you check the
+ * confirmation code from the slave for any communication, and retry a few
+ * times in case of failure. */
+
+#ifndef __CROS_EC_ONEWIRE_H
+#define __CROS_EC_ONEWIRE_H
+
+#include "common.h"
+
+/* Initialize the module. */
+int onewire_init(void);
+
+/* Reset the 1-wire bus.  Returns error if presence detect fails. */
+int onewire_reset(void);
+
+/* Read a byte from the 1-wire bus.  Returns the byte. */
+int onewire_read(void);
+
+/* Write a byte to the 1-wire bus. */
+void onewire_write(int data);
+
+#endif  /* __CROS_EC_ONEWIRE_H */

include/power_led.h

@@ -0,0 +1,24 @@
+/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Power LED control for Chrome EC */
+
+#ifndef __CROS_EC_POWER_LED_H
+#define __CROS_EC_POWER_LED_H
+
+#include "common.h"
+
+enum powerled_color {
+	POWERLED_OFF = 0,
+	POWERLED_RED,
+	POWERLED_YELLOW,
+	POWERLED_GREEN,
+	POWERLED_COLOR_COUNT  /* Number of colors, not a color itself */
+};
+
+/* Set the power adapter LED to the specified color. */
+int powerled_set(enum powerled_color color);
+
+#endif  /* __CROS_EC_POWER_LED_H */