Move I2C arbitration to its own file

It's only board-specific in that we've only needed it on snow so far.
But by that logic, x86_power would be board specific because we've
only needed it on link.

No functionality change, just moving code between files and renaming
the interface to indicate it's not board-specific.

BUG=chrome-os-partner:18343
BRANCH=none
TEST=build daisy,snow,spring

Change-Id: I35debdaa71829d55a2fbc5d3c62b2aaf6e467633
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/45879

7 files changed, 157 insertions, 147 deletions

diff --git a/board/snow/board.c b/board/snow/board.c
index 3964f15f3a..2f5900340b 100644
--- a/board/snow/board.c
+++ b/board/snow/board.c
@@ -229,34 +229,6 @@ void board_power_led_config(enum powerled_config config)
 	}
 }
 
-enum {
-	/* Time between requesting bus and deciding that we have it */
-	BUS_SLEW_DELAY_US	= 10,
-
-	/* Time between retrying to see if the AP has released the bus */
-	BUS_WAIT_RETRY_US	= 3000,
-
-	/* Time to wait until the bus becomes free */
-	BUS_WAIT_FREE_US	= 100 * 1000,
-};
-
-/*
- * This reflects the desired value of GPIO_EC_CLAIM to ensure that the
- * GPIO is driven correctly when re-enabled before AP power on.
- */
-static char i2c_claimed_by_ec;
-
-static void board_pre_init_hook(void)
-{
-#ifdef CONFIG_ARBITRATE_I2C
-	gpio_set_flags(GPIO_AP_CLAIM, GPIO_PULL_UP);
-	gpio_set_level(GPIO_EC_CLAIM, i2c_claimed_by_ec ? 0 : 1);
-	gpio_set_flags(GPIO_EC_CLAIM, GPIO_OUTPUT);
-	usleep(BUS_SLEW_DELAY_US);
-#endif
-}
-DECLARE_HOOK(HOOK_CHIPSET_PRE_INIT, board_pre_init_hook, HOOK_PRIO_DEFAULT);
-
 static void board_startup_hook(void)
 {
 	gpio_set_flags(GPIO_SUSPEND_L, INT_BOTH_PULL_UP);
@@ -267,77 +239,9 @@ static void board_shutdown_hook(void)
 {
 	/* Disable pull-up on SUSPEND_L during shutdown to prevent leakage */
 	gpio_set_flags(GPIO_SUSPEND_L, INT_BOTH_FLOATING);
-
-#ifdef CONFIG_ARBITRATE_I2C
-	gpio_set_flags(GPIO_AP_CLAIM, GPIO_INPUT);
-	gpio_set_flags(GPIO_EC_CLAIM, GPIO_INPUT);
-#endif
 }
 DECLARE_HOOK(HOOK_CHIPSET_SHUTDOWN, board_shutdown_hook, HOOK_PRIO_DEFAULT);
 
-#ifdef CONFIG_ARBITRATE_I2C
-
-int board_i2c_claim(int port)
-{
-	timestamp_t start;
-
-	if (port != I2C_PORT_HOST)
-		return EC_SUCCESS;
-
-	/* If AP is off, we have the bus */
-	if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
-		i2c_claimed_by_ec = 1;
-		return EC_SUCCESS;
-	}
-
-	/* Start a round of trying to claim the bus */
-	start = get_time();
-	do {
-		timestamp_t start_retry;
-		int waiting = 0;
-
-		/* Indicate that we want to claim the bus */
-		gpio_set_level(GPIO_EC_CLAIM, 0);
-		usleep(BUS_SLEW_DELAY_US);
-
-		/* Wait for the AP to release it */
-		start_retry = get_time();
-		while (time_since32(start_retry) < BUS_WAIT_RETRY_US) {
-			if (gpio_get_level(GPIO_AP_CLAIM)) {
-				/* We got it, so return */
-				i2c_claimed_by_ec = 1;
-				return EC_SUCCESS;
-			}
-
-			if (!waiting)
-				waiting = 1;
-		}
-
-		/* It didn't release, so give up, wait, and try again */
-		gpio_set_level(GPIO_EC_CLAIM, 1);
-
-		usleep(BUS_WAIT_RETRY_US);
-	} while (time_since32(start) < BUS_WAIT_FREE_US);
-
-	gpio_set_level(GPIO_EC_CLAIM, 1);
-	usleep(BUS_SLEW_DELAY_US);
-	i2c_claimed_by_ec = 0;
-
-	panic_puts("Unable to access I2C bus (arbitration timeout)\n");
-	return EC_ERROR_BUSY;
-}
-
-void board_i2c_release(int port)
-{
-	if (port == I2C_PORT_HOST) {
-		/* Release our claim */
-		gpio_set_level(GPIO_EC_CLAIM, 1);
-		usleep(BUS_SLEW_DELAY_US);
-		i2c_claimed_by_ec = 0;
-	}
-}
-#endif /* CONFIG_ARBITRATE_I2C */
-
 /*
  * Force the pmic to reset completely.  This forces an entire system reset,
  * and therefore should never return
diff --git a/board/snow/board.h b/board/snow/board.h
index 89e77e4f0c..5f2bb4c5c9 100644
--- a/board/snow/board.h
+++ b/board/snow/board.h
@@ -24,6 +24,7 @@
 #define CONFIG_CONFIGURE_BOARD_LATE
 #define CONFIG_HOST_COMMAND_STATUS
 #define CONFIG_I2C
+#define CONFIG_I2C_ARBITRATION
 #undef  CONFIG_TASK_PROFILING
 #define CONFIG_WATCHDOG_HELP
 
@@ -50,7 +51,6 @@
 #define I2C_PORT_BATTERY I2C_PORT_HOST
 #define I2C_PORT_CHARGER I2C_PORT_HOST
 #define I2C_PORT_SLAVE 1
-#define CONFIG_ARBITRATE_I2C I2C_PORT_HOST
 
 #define GPIO_AP_CLAIM	GPIO_SPI1_NSS	/* AP claims bus */
 #define GPIO_EC_CLAIM	GPIO_SPI1_MISO	/* EC claims bus */
diff --git a/chip/stm32/i2c.c b/chip/stm32/i2c.c
index e2f1a9fbd8..a682883c89 100644
--- a/chip/stm32/i2c.c
+++ b/chip/stm32/i2c.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+/* 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.
  */
@@ -12,6 +12,7 @@
 #include "hooks.h"
 #include "host_command.h"
 #include "i2c.h"
+#include "i2c_arbitration.h"
 #include "registers.h"
 #include "task.h"
 #include "timer.h"
@@ -123,22 +124,6 @@ static inline void disable_ack(int port)
 	STM32_I2C_CR1(port) &= ~(1 << 10);
 }
 
-int __board_i2c_claim(int port)
-{
-	return 0;
-}
-
-int board_i2c_claim(int port)
-	__attribute__((weak, alias("__board_i2c_claim")));
-
-
-void __board_i2c_release(int port)
-{
-}
-
-void board_i2c_release(int port)
-	__attribute__((weak, alias("__board_i2c_release")));
-
 static void i2c_init_port(unsigned int port);
 
 static int i2c_write_raw_slave(int port, void *buf, int len)
@@ -464,9 +449,9 @@ static void i2c_init_port(unsigned int port)
 
 	if (!(STM32_RCC_APB1ENR & (1 << i2c_clock_bit[port]))) {
 		/* Only unwedge the bus if the clock is off */
-		if (board_i2c_claim(port) == EC_SUCCESS) {
+		if (i2c_claim(port) == EC_SUCCESS) {
 			unwedge_i2c_bus(port);
-			board_i2c_release(port);
+			i2c_release(port);
 		}
 
 		/* enable I2C2 clock */
@@ -848,7 +833,7 @@ static int i2c_xfer(int port, int slave_addr, uint8_t *out, int out_bytes,
 	disable_sleep(SLEEP_MASK_I2C);
 	mutex_lock(&i2c_mutex);
 
-	if (board_i2c_claim(port)) {
+	if (i2c_claim(port)) {
 		rv = EC_ERROR_BUSY;
 		goto err_claim;
 	}
@@ -863,7 +848,7 @@ static int i2c_xfer(int port, int slave_addr, uint8_t *out, int out_bytes,
 
 	enable_i2c_interrupt(port);
 
-	board_i2c_release(port);
+	i2c_release(port);
 
 err_claim:
 	mutex_unlock(&i2c_mutex);
diff --git a/common/build.mk b/common/build.mk
index 7fb75d3a39..a490cf9479 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -19,6 +19,7 @@ common-$(CONFIG_EOPTION)+=eoption.o
 common-$(CONFIG_EXTPOWER_GPIO)+=extpower_gpio.o
 common-$(CONFIG_FLASH)+=flash_common.o fmap.o
 common-$(CONFIG_I2C)+=i2c_commands.o
+common-$(CONFIG_I2C_ARBITRATION)+=i2c_arbitration.o
 common-$(CONFIG_IR357x)+=ir357x.o
 common-$(CONFIG_KEYBOARD_TEST)+=keyboard_test.o
 common-$(CONFIG_LP5562)+=lp5562.o
diff --git a/common/i2c_arbitration.c b/common/i2c_arbitration.c
new file mode 100644
index 0000000000..70b4b81dcd
--- /dev/null
+++ b/common/i2c_arbitration.c
@@ -0,0 +1,104 @@
+/* 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.
+ */
+/* I2C arbitration using a pair of GPIO lines */
+
+#include "chipset.h"
+#include "common.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "i2c.h"
+#include "timer.h"
+#include "util.h"
+
+/* Time between requesting bus and deciding that we have it */
+#define BUS_SLEW_DELAY_US 10
+
+/* Time between retrying to see if the AP has released the bus */
+#define BUS_WAIT_RETRY_US 3000
+
+/* Time to wait until the bus becomes free */
+#define BUS_WAIT_FREE_US (100 * 1000)
+
+/*
+ * This reflects the desired value of GPIO_EC_CLAIM to ensure that the
+ * GPIO is driven correctly when re-enabled before AP power on.
+ */
+static char i2c_claimed_by_ec;
+
+int i2c_claim(int port)
+{
+	timestamp_t start;
+
+	if (port != I2C_PORT_HOST)
+		return EC_SUCCESS;
+
+	/* If AP is off, we have the bus */
+	if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
+		i2c_claimed_by_ec = 1;
+		return EC_SUCCESS;
+	}
+
+	/* Start a round of trying to claim the bus */
+	start = get_time();
+	do {
+		timestamp_t start_retry;
+		int waiting = 0;
+
+		/* Indicate that we want to claim the bus */
+		gpio_set_level(GPIO_EC_CLAIM, 0);
+		usleep(BUS_SLEW_DELAY_US);
+
+		/* Wait for the AP to release it */
+		start_retry = get_time();
+		while (time_since32(start_retry) < BUS_WAIT_RETRY_US) {
+			if (gpio_get_level(GPIO_AP_CLAIM)) {
+				/* We got it, so return */
+				i2c_claimed_by_ec = 1;
+				return EC_SUCCESS;
+			}
+
+			if (!waiting)
+				waiting = 1;
+		}
+
+		/* It didn't release, so give up, wait, and try again */
+		gpio_set_level(GPIO_EC_CLAIM, 1);
+
+		usleep(BUS_WAIT_RETRY_US);
+	} while (time_since32(start) < BUS_WAIT_FREE_US);
+
+	gpio_set_level(GPIO_EC_CLAIM, 1);
+	usleep(BUS_SLEW_DELAY_US);
+	i2c_claimed_by_ec = 0;
+
+	panic_puts("Unable to access I2C bus (arbitration timeout)\n");
+	return EC_ERROR_BUSY;
+}
+
+void i2c_release(int port)
+{
+	if (port == I2C_PORT_HOST) {
+		/* Release our claim */
+		gpio_set_level(GPIO_EC_CLAIM, 1);
+		usleep(BUS_SLEW_DELAY_US);
+		i2c_claimed_by_ec = 0;
+	}
+}
+
+static void i2c_pre_init_hook(void)
+{
+	gpio_set_flags(GPIO_AP_CLAIM, GPIO_PULL_UP);
+	gpio_set_level(GPIO_EC_CLAIM, i2c_claimed_by_ec ? 0 : 1);
+	gpio_set_flags(GPIO_EC_CLAIM, GPIO_OUTPUT);
+	usleep(BUS_SLEW_DELAY_US);
+}
+DECLARE_HOOK(HOOK_CHIPSET_PRE_INIT, i2c_pre_init_hook, HOOK_PRIO_DEFAULT);
+
+static void i2c_shutdown_hook(void)
+{
+	gpio_set_flags(GPIO_AP_CLAIM, GPIO_INPUT);
+	gpio_set_flags(GPIO_EC_CLAIM, GPIO_INPUT);
+}
+DECLARE_HOOK(HOOK_CHIPSET_SHUTDOWN, i2c_shutdown_hook, HOOK_PRIO_DEFAULT);
diff --git a/include/i2c.h b/include/i2c.h
index dbf933e102..d14008a2d0 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+/* 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.
  */
@@ -48,32 +48,4 @@ int i2c_write8(int port, int slave_addr, int offset, int data);
 int i2c_read_string(int port, int slave_addr, int offset, uint8_t *data,
 			int len);
 
-/**
- * Claim an I2C port for use in master mode
- *
- * If this function succeed, then you must later call board_i2c_release()
- * to release the claim.
- *
- * This function may optionally be implemented by a board file. If provided
- * then it should check the port number and arbitrate as needed.
- *
- * This function will not be called to claim an already-claimed port.
- *
- * @param port	Port to claim (0 for first, 1 for second, etc.)
- * @return 0 if claimed successfully, -1 if it is in use
- */
-int board_i2c_claim(int port);
-
-/**
- * Release an I2C port (after previously being claimed)
- *
- * This function may optionally be implemented by a board file. If provided
- * then it should check the port number and arbitrate as needed.
- *
- * This function will not be called to release an already-released port.
- *
- * @param port	Port to claim (0 for first, 1 for second, etc.)
- */
-void board_i2c_release(int port);
-
 #endif  /* __CROS_EC_I2C_H */
diff --git a/include/i2c_arbitration.h b/include/i2c_arbitration.h
new file mode 100644
index 0000000000..cf4d39d247
--- /dev/null
+++ b/include/i2c_arbitration.h
@@ -0,0 +1,44 @@
+/* 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.
+ */
+
+/* I2C arbitration for Chrome EC */
+
+#ifndef __CROS_EC_I2C_ARBITRATION_H
+#define __CROS_EC_I2C_ARBITRATION_H
+
+#include "common.h"
+
+#ifdef CONFIG_I2C_ARBITRATION
+
+/**
+ * Claim an I2C port for use in master mode.
+ *
+ * If this function succeeds, you must later call i2c_release() to release the
+ * claim.
+ *
+ * This function must not be called to claim an already-claimed port.
+ *
+ * @param port	Port to claim (0 for first, 1 for second, etc.)
+ * @return 0 if claimed successfully, -1 if it is in use
+ */
+int i2c_claim(int port);
+
+/**
+ * Release an I2C port (after previously being claimed)
+ *
+ * This function must not be called to release an already-released port.
+ *
+ * @param port	Port to claim (0 for first, 1 for second, etc.)
+ */
+void i2c_release(int port);
+
+#else
+
+static inline int i2c_claim(int port) { return EC_SUCCESS; }
+static inline void i2c_release(int port) {}
+
+#endif
+
+#endif  /* __CROS_EC_I2C_ARBITRATION_H */