Add ALS driver for light sensors connected to EC

This adds the driver and a console command to read an Intersil ISL29305
light sensor connected to the EC.

BUG=chrome-os-partner:23380
BRANCH=samus
TEST=manual

Run the "als" command from the EC console, while pointing the sensor in
various directions. It should give higher numbers when facing a light
source.  If you get "Error 1", it means the ALS isn't powered.

Change-Id: I855ed64dab7fc60e29126ab3e97669be24dc6a64
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/176056

9 files changed, 184 insertions, 0 deletions

diff --git a/board/samus/board.c b/board/samus/board.c
index db8639acb9..d7f5b58e5f 100644
--- a/board/samus/board.c
+++ b/board/samus/board.c
@@ -4,12 +4,14 @@
  */
 /* EC for Samus board configuration */
 
+#include "als.h"
 #include "adc.h"
 #include "adc_chip.h"
 #include "backlight.h"
 #include "chipset_x86_common.h"
 #include "common.h"
 #include "driver/temp_sensor/tmp006.h"
+#include "driver/als_isl29035.h"
 #include "extpower.h"
 #include "fan.h"
 #include "gpio.h"
@@ -267,6 +269,13 @@ const struct temp_sensor_t temp_sensors[] = {
 };
 BUILD_ASSERT(ARRAY_SIZE(temp_sensors) == TEMP_SENSOR_COUNT);
 
+/* ALS instances. Must be in same order as enum als_id. */
+struct als_t als[] = {
+	{"ISL", isl29035_read_lux},
+};
+BUILD_ASSERT(ARRAY_SIZE(als) == ALS_COUNT);
+
+
 /* Thermal limits for each temp sensor. All temps are in degrees K. Must be in
  * same order as enum temp_sensor_id. To always ignore any temp, use 0.
  */
diff --git a/board/samus/board.h b/board/samus/board.h
index e32ee8beb3..8e124b066e 100644
--- a/board/samus/board.h
+++ b/board/samus/board.h
@@ -15,6 +15,8 @@
 #undef HEY_USE_BUILTIN_CLKRUN
 
 /* Optional features */
+#define CONFIG_ALS
+#define CONFIG_ALS_ISL29035
 #define CONFIG_BOARD_VERSION
 #define CONFIG_CHIPSET_X86
 #define CONFIG_CHIPSET_CAN_THROTTLE
@@ -215,6 +217,13 @@ enum temp_sensor_id {
 /* The number of TMP006 sensor chips on the board. */
 #define TMP006_COUNT 6
 
+/* Light sensors attached to the EC. */
+enum als_id {
+	ALS_ISL29035 = 0,
+
+	ALS_COUNT,
+};
+
 /* Known board versions for system_get_board_version(). */
 enum board_version {
 	BOARD_VERSION_PROTO1 = 0,
diff --git a/common/als.c b/common/als.c
new file mode 100644
index 0000000000..bb2854132f
--- /dev/null
+++ b/common/als.c
@@ -0,0 +1,45 @@
+/* Copyright (c) 2013 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.
+ */
+
+/* This provides the interface for any Ambient Light Sensors that are connected
+ * to the EC instead of the AP.
+ */
+
+#include "als.h"
+#include "common.h"
+#include "console.h"
+#include "host_command.h"
+#include "util.h"
+
+int als_read(enum als_id id, int *lux)
+{
+	return als[id].read(lux);
+}
+
+/*****************************************************************************/
+/* Console commands */
+
+static int command_als(int argc, char **argv)
+{
+	int i, rv, val;
+
+	for (i = 0; i < ALS_COUNT; i++) {
+		ccprintf("%s: ", als[i].name);
+		rv = als_read(i, &val);
+		switch (rv) {
+		case EC_SUCCESS:
+			ccprintf("%d lux\n", val);
+			break;
+		default:
+			ccprintf("Error %d\n", rv);
+		}
+	}
+
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(als, command_als,
+			NULL,
+			"Print ALS values",
+			NULL);
diff --git a/common/build.mk b/common/build.mk
index 132fd62783..8cf26fab6e 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -10,6 +10,7 @@ common-y=main.o util.o console_output.o uart_buffering.o
 common-y+=memory_commands.o shared_mem.o system.o hooks.o
 common-y+=gpio.o version.o printf.o queue.o
 
+common-$(CONFIG_ALS)+=als.o
 common-$(CONFIG_BACKLIGHT_LID)+=backlight_lid.o
 # TODO(crosbug.com/p/23821): Why do these include battery_common but
 # the other batteries don't?  Perhaps should use CONFIG_CMD_BATTERY
diff --git a/driver/als_isl29035.c b/driver/als_isl29035.c
new file mode 100644
index 0000000000..13e5d77c14
--- /dev/null
+++ b/driver/als_isl29035.c
@@ -0,0 +1,65 @@
+/* Copyright (c) 2013 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.
+ *
+ * Intersil ILS29035 light sensor driver
+ */
+
+#include "driver/als_isl29035.h"
+#include "common.h"
+#include "i2c.h"
+#include "timer.h"
+
+/* I2C interface */
+#define ILS29035_I2C_ADDR       0x88
+#define ILS29035_REG_COMMAND_I  0
+#define ILS29035_REG_COMMAND_II 1
+#define ILS29035_REG_DATA_LSB   2
+#define ILS29035_REG_DATA_MSB   3
+#define ILS29035_REG_INT_LT_LSB 4
+#define ILS29035_REG_INT_LT_MSB 5
+#define ILS29035_REG_INT_HT_LSB 6
+#define ILS29035_REG_INT_HT_MSB 7
+#define ILS29035_REG_ID         15
+
+int isl29035_read_lux(int *lux)
+{
+	int rv, lsb, msb, data;
+
+	/* Tell it to read once */
+	rv = i2c_write8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
+			ILS29035_REG_COMMAND_I, 0x20);
+	if (rv)
+		return rv;
+
+	/* The highest precision (default) should take ~90ms */
+	usleep(100 * MSEC);
+
+	/* NOTE: It is necessary to read the LSB first, then the MSB. If you do
+	 * it in the opposite order, the results are not correct. This is
+	 * apparently an undocumented "feature".
+	 */
+
+	/* Read lsb */
+	rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
+		       ILS29035_REG_DATA_LSB, &lsb);
+	if (rv)
+		return rv;
+
+	/* Read msb */
+	rv = i2c_read8(I2C_PORT_ALS, ILS29035_I2C_ADDR,
+		       ILS29035_REG_DATA_MSB, &msb);
+	if (rv)
+		return rv;
+
+	data = (msb << 8) | lsb;
+
+	/*
+	 * The default power-on values will give 16 bits of precision:
+	 * 0x0000-0xffff indicates 0-1000 lux. If you change the defaults,
+	 * you'll need to change the scale factor accordingly.
+	 */
+	*lux = data * 1000 / 0xffff;
+
+	return EC_SUCCESS;
+}
diff --git a/driver/als_isl29035.h b/driver/als_isl29035.h
new file mode 100644
index 0000000000..8d3a4ac0f5
--- /dev/null
+++ b/driver/als_isl29035.h
@@ -0,0 +1,13 @@
+/* Copyright (c) 2013 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.
+ *
+ * Intersil ILS29035 light sensor driver
+ */
+
+#ifndef __CROS_EC_ALS_ILS29035_H
+#define __CROS_EC_ALS_ILS29035_H
+
+int isl29035_read_lux(int *lux);
+
+#endif	/* __CROS_EC_ALS_ILS29035_H */
diff --git a/driver/build.mk b/driver/build.mk
index 013cfb4159..59e27f1efa 100644
--- a/driver/build.mk
+++ b/driver/build.mk
@@ -6,6 +6,9 @@
 # Drivers for off-chip devices
 #
 
+# ALS drivers
+driver-$(CONFIG_ALS_ISL29035)+=als_isl29035.o
+
 # Batteries
 driver-$(CONFIG_BATTERY_BQ20Z453)+=battery/bq20z453.o
 driver-$(CONFIG_BATTERY_BQ27541)+=battery/bq27541.o
diff --git a/include/als.h b/include/als.h
new file mode 100644
index 0000000000..e229a3791f
--- /dev/null
+++ b/include/als.h
@@ -0,0 +1,32 @@
+/* Copyright (c) 2013 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.
+ */
+
+#ifndef __CROS_EC_ALS_H
+#define __CROS_EC_ALS_H
+
+#include "common.h"
+
+/* Defined in board.h */
+enum als_id;
+
+/* Initialized in board.c */
+struct als_t {
+	const char const *name;
+	int (*read)(int *lux);
+};
+
+extern struct als_t als[];
+
+/**
+ * Read an ALS
+ *
+ * @param id		Which one?
+ * @param lux	        Put value here
+ *
+ * @return EC_SUCCESS, or non-zero if error.
+ */
+int als_read(enum als_id id, int *lux);
+
+#endif  /* __CROS_EC_ALS_H */
diff --git a/include/config.h b/include/config.h
index c6e151158e..002d509def 100644
--- a/include/config.h
+++ b/include/config.h
@@ -46,6 +46,13 @@
 #undef CONFIG_ADC_CLOCK
 
 /*
+ * Some ALS modules may be connected to the EC. We need the command, and
+ * specific drivers for each module.
+ */
+#undef CONFIG_ALS
+#undef CONFIG_ALS_ISL29035
+
+/*
  * Support controlling the display backlight based on the state of the lid
  * switch.  The EC will disable the backlight when the lid is closed.
  */