Add hooks module so modules can be notified of system-level events.

This will be used for sleep/wake/sysjump/etc.  For now it's just wired
up to clock frequency changing.

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

BUG=none
TEST=manual: use nopll command, should still work

Change-Id: Iedcea5830bc18eacfd955c29b8f793aba8905dd8

13 files changed, 174 insertions, 71 deletions

diff --git a/chip/lm4/clock.c b/chip/lm4/clock.c
index 694f1bc1b9..12a1896ff7 100644
--- a/chip/lm4/clock.c
+++ b/chip/lm4/clock.c
@@ -10,6 +10,7 @@
 #include "config.h"
 #include "console.h"
 #include "gpio.h"
+#include "hooks.h"
 #include "registers.h"
 #include "system.h"
 #include "task.h"
@@ -178,34 +179,10 @@ static int command_sleep(int argc, char **argv)
 DECLARE_CONSOLE_COMMAND(sleep, command_sleep);
 
 
-/* TODO: temporary holding place for notifying modules of clock change.  Should
- * be moved to main.c after we finish measuring the power savings, so the clock
- * frequency is automatically dropped after verified boot. */
-#include "i2c.h"
-#include "hwtimer.h"
-#include "peci.h"
-#include "watchdog.h"
-
 static int command_disable_pll(int argc, char **argv)
 {
-	int freq;
-
-	clock_disable_pll();
-
 	/* Notify modules of frequency change */
-	freq = clock_get_freq();
-	hwtimer_clock_changed(freq);
-#ifdef CONFIG_TASK_WATCHDOG
-	watchdog_clock_changed(freq);
-#endif
-#ifdef CONFIG_I2C
-	i2c_clock_changed(freq);
-#endif
-#ifdef CONFIG_PECI
-	peci_clock_changed(freq);
-#endif
-
-	return EC_SUCCESS;
+	return hook_notify(HOOK_FREQ_CHANGE, 0);
 }
 DECLARE_CONSOLE_COMMAND(nopll, command_disable_pll);
 
diff --git a/chip/lm4/hwtimer.c b/chip/lm4/hwtimer.c
index a45f74705d..41e737b10d 100644
--- a/chip/lm4/hwtimer.c
+++ b/chip/lm4/hwtimer.c
@@ -7,6 +7,7 @@
 
 #include "board.h"
 #include "clock.h"
+#include "hooks.h"
 #include "hwtimer.h"
 #include "registers.h"
 #include "task.h"
@@ -21,22 +22,26 @@ void __hw_clock_event_set(uint32_t deadline)
 	LM4_TIMER_IMR(6) |= 0x10;
 }
 
+
 uint32_t __hw_clock_event_get(void)
 {
 	return 0xffffffff - LM4_TIMER_TAMATCHR(6);
 }
 
+
 void __hw_clock_event_clear(void)
 {
 	/* Disable the match interrupt */
 	LM4_TIMER_IMR(6) &= ~0x10;
 }
 
+
 uint32_t __hw_clock_source_read(void)
 {
 	return 0xffffffff - LM4_TIMER_TAV(6);
 }
 
+
 static void __hw_clock_source_irq(void)
 {
 	uint32_t status = LM4_TIMER_RIS(6);
@@ -53,12 +58,15 @@ static void __hw_clock_source_irq(void)
 DECLARE_IRQ(LM4_IRQ_TIMERW0A, __hw_clock_source_irq, 1);
 
 
-void hwtimer_clock_changed(int freq)
+static int update_prescaler(void)
 {
 	/* Set the prescaler to increment every microsecond.  This takes
 	 * effect immediately, because the TAILD bit in TAMR is clear. */
-	LM4_TIMER_TAPR(6) = freq / US_PER_SECOND;
+	LM4_TIMER_TAPR(6) = clock_get_freq() / US_PER_SECOND;
+
+	return EC_SUCCESS;
 }
+DECLARE_HOOK(HOOK_FREQ_CHANGE, update_prescaler, HOOK_PRIO_DEFAULT);
 
 
 int __hw_clock_source_init(void)
@@ -80,8 +88,8 @@ int __hw_clock_source_init(void)
 	/* 32-bit timer mode */
 	LM4_TIMER_CFG(6) = 4;
 
-	/* Set initial clock frequency */
-	hwtimer_clock_changed(clock_get_freq());
+	/* Set initial prescaler */
+	update_prescaler();
 
 	/* Periodic mode, counting down */
 	LM4_TIMER_TAMR(6) = 0x22;
diff --git a/chip/lm4/i2c.c b/chip/lm4/i2c.c
index 131a84a584..c712adf641 100644
--- a/chip/lm4/i2c.c
+++ b/chip/lm4/i2c.c
@@ -9,6 +9,7 @@
 #include "clock.h"
 #include "console.h"
 #include "gpio.h"
+#include "hooks.h"
 #include "i2c.h"
 #include "task.h"
 #include "timer.h"
@@ -260,8 +261,10 @@ exit:
 }
 
 
-void i2c_clock_changed(int freq)
+static int i2c_freq_changed(void)
 {
+	int freq = clock_get_freq();
+
 	LM4_I2C_MTPR(I2C_PORT_THERMAL) =
 		(freq / (I2C_SPEED_THERMAL * 10 * 2)) - 1;
 	LM4_I2C_MTPR(I2C_PORT_BATTERY) =
@@ -270,7 +273,10 @@ void i2c_clock_changed(int freq)
 		(freq / (I2C_SPEED_CHARGER * 10 * 2)) - 1;
 	LM4_I2C_MTPR(I2C_PORT_LIGHTBAR) =
 		(freq / (I2C_SPEED_LIGHTBAR * 10 * 2)) - 1;
+
+	return EC_SUCCESS;
 }
+DECLARE_HOOK(HOOK_FREQ_CHANGE, i2c_freq_changed, HOOK_PRIO_DEFAULT + 1);
 
 /*****************************************************************************/
 /* Interrupt handlers */
@@ -307,7 +313,6 @@ DECLARE_IRQ(LM4_IRQ_I2C5, i2c5_interrupt, 2);
 /*****************************************************************************/
 /* Console commands */
 
-
 static void scan_bus(int port, char *desc)
 {
 	int rv;
@@ -457,7 +462,7 @@ int i2c_init(void)
 	LM4_I2C_MCR(I2C_PORT_LIGHTBAR) = 0x10;
 
 	/* Set initial clock frequency */
-	i2c_clock_changed(clock_get_freq());
+	i2c_freq_changed();
 
 	/* Enable irqs */
 	task_enable_irq(LM4_IRQ_I2C0);
diff --git a/chip/lm4/peci.c b/chip/lm4/peci.c
index 2dbbd914b3..0e7540fa10 100644
--- a/chip/lm4/peci.c
+++ b/chip/lm4/peci.c
@@ -9,6 +9,7 @@
 #include "clock.h"
 #include "console.h"
 #include "gpio.h"
+#include "hooks.h"
 #include "peci.h"
 #include "registers.h"
 #include "temp_sensor.h"
@@ -70,8 +71,9 @@ int peci_temp_sensor_get_val(int idx)
 }
 
 
-void peci_clock_changed(int freq)
+static int peci_freq_changed(void)
 {
+	int freq = clock_get_freq();
 	int baud;
 
 	/* Disable polling while reconfiguring */
@@ -88,7 +90,10 @@ void peci_clock_changed(int freq)
 
 	/* Set up temperature monitoring to report in degrees K */
 	LM4_PECI_CTL = ((PECI_TJMAX + 273) << 22) | 0x2001;
+
+	return EC_SUCCESS;
 }
+DECLARE_HOOK(HOOK_FREQ_CHANGE, peci_freq_changed, HOOK_PRIO_DEFAULT - 1);
 
 /*****************************************************************************/
 /* Console commands */
@@ -121,7 +126,7 @@ int peci_init(void)
 	configure_gpios();
 
 	/* Set initial clock frequency */
-	peci_clock_changed(clock_get_freq());
+	peci_freq_changed();
 
 	return EC_SUCCESS;
 }
diff --git a/chip/lm4/watchdog.c b/chip/lm4/watchdog.c
index 65c5ad2d2a..c13414c20e 100644
--- a/chip/lm4/watchdog.c
+++ b/chip/lm4/watchdog.c
@@ -11,6 +11,7 @@
 #include "config.h"
 #include "registers.h"
 #include "gpio.h"
+#include "hooks.h"
 #include "task.h"
 #include "timer.h"
 #include "uart.h"
@@ -76,6 +77,7 @@ void watchdog_trace(uint32_t excep_lr, uint32_t excep_sp)
 	uart_emergency_flush();
 }
 
+
 void IRQ_HANDLER(LM4_IRQ_WATCHDOG)(void) __attribute__((naked));
 void IRQ_HANDLER(LM4_IRQ_WATCHDOG)(void)
 {
@@ -118,11 +120,13 @@ void watchdog_reload(void)
 }
 
 
-void watchdog_clock_changed(int freq)
+static int watchdog_freq_changed(void)
 {
 	/* Set the timeout period */
-	watchdog_period = WATCHDOG_PERIOD_MS * (freq / 1000);
+	watchdog_period = WATCHDOG_PERIOD_MS * (clock_get_freq() / 1000);
+	return EC_SUCCESS;
 }
+DECLARE_HOOK(HOOK_FREQ_CHANGE, watchdog_freq_changed, HOOK_PRIO_DEFAULT);
 
 
 int watchdog_init(void)
@@ -138,7 +142,7 @@ int watchdog_init(void)
 	LM4_WATCHDOG_LOCK(0) = LM4_WATCHDOG_MAGIC_WORD;
 
 	/* Set initial timeout period */
-	watchdog_clock_changed(clock_get_freq());
+	watchdog_freq_changed();
 	LM4_WATCHDOG_LOAD(0) = watchdog_period;
 
 	/* De-activate the watchdog when the JTAG stops the CPU */
diff --git a/common/build.mk b/common/build.mk
index 2144973ba1..dcece87b59 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -6,7 +6,7 @@
 #
 
 common-y=main.o message.o util.o console.o vboot.o uart_buffering.o
-common-y+=memory_commands.o shared_mem.o system_common.o
+common-y+=memory_commands.o shared_mem.o system_common.o hooks.o
 common-y+=gpio_commands.o version.o
 common-$(CONFIG_BATTERY_ATL706486)+=battery_atl706486.o
 common-$(CONFIG_CHARGER_BQ24725)+=charger_bq24725.o
diff --git a/common/hooks.c b/common/hooks.c
new file mode 100644
index 0000000000..94bf2627fb
--- /dev/null
+++ b/common/hooks.c
@@ -0,0 +1,63 @@
+/* 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.
+ */
+
+/* System hooks for Chrome EC */
+
+#include "hooks.h"
+#include "uart.h"
+#include "util.h"
+
+/* Hooks are described in special sections */
+extern const struct hook_data __hooks_freq_change[];
+extern const struct hook_data __hooks_freq_change_end[];
+
+
+int hook_notify(enum hook_type type, int stop_on_error)
+{
+	const struct hook_data *start, *end, *p;
+	int count, called = 0;
+	int last_prio = HOOK_PRIO_FIRST - 1, prio;
+	int rv_error = EC_SUCCESS, rv;
+
+	/* Get the start and end pointers for the hook type */
+	switch (type) {
+	case HOOK_FREQ_CHANGE:
+		start = __hooks_freq_change;
+		end = __hooks_freq_change_end;
+		break;
+	default:
+		/* Unhandled hook type */
+		return EC_ERROR_UNKNOWN;
+	}
+
+	count = ((uint32_t)end - (uint32_t)start) / sizeof(struct hook_data);
+
+	/* Call all the hooks in priority order */
+	while (called < count) {
+		/* Find the lowest remaining priority */
+		for (p = start, prio = HOOK_PRIO_LAST + 1; p < end; p++) {
+			if (p->priority < prio && p->priority > last_prio)
+				prio = p->priority;
+		}
+		last_prio = prio;
+
+		/* Call all the hooks with that priority */
+		for (p = start; p < end; p++) {
+			if (p->priority == prio) {
+				called++;
+				rv = p->routine();
+				if (rv != EC_SUCCESS) {
+					if (stop_on_error)
+						return rv;
+					else if (rv_error == EC_SUCCESS)
+						rv_error = rv;
+				}
+			}
+		}
+	}
+
+	/* Return the first error seen, if any */
+	return rv_error;
+}
diff --git a/core/cortex-m/ec.lds.S b/core/cortex-m/ec.lds.S
index 04c95f85e4..21fddb3f5e 100644
--- a/core/cortex-m/ec.lds.S
+++ b/core/cortex-m/ec.lds.S
@@ -34,13 +34,24 @@ SECTIONS
         __irqprio = .;
         *(.rodata.irqprio)
         __irqprio_end = .;
+
         . = ALIGN(4);
         __cmds = .;
         *(.rodata.cmds)
         __cmds_end = .;
+
+        . = ALIGN(4);
         __hcmds = .;
         *(.rodata.hcmds)
         __hcmds_end = .;
+
+        . = ALIGN(4);
+        __hooks_freq_change = .;
+        *(.rodata.HOOK_FREQ_CHANGE)
+        __hooks_freq_change_end = .;
+
+
+        . = ALIGN(4);
         *(.rodata*)
         . = ALIGN(4);
 #ifdef COMPILE_FOR_RAM
diff --git a/include/hooks.h b/include/hooks.h
new file mode 100644
index 0000000000..3d3a834e25
--- /dev/null
+++ b/include/hooks.h
@@ -0,0 +1,48 @@
+/* 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.
+ */
+
+/* System hooks for Chrome EC */
+
+#ifndef __CROS_EC_HOOKS_H
+#define __CROS_EC_HOOKS_H
+
+#include "common.h"
+
+enum hook_priority {
+	HOOK_PRIO_FIRST = 1,       /* Highest priority */
+	HOOK_PRIO_DEFAULT = 5000,  /* Default priority */
+	HOOK_PRIO_LAST = 9999      /* Lowest priority */
+};
+
+enum hook_type {
+	HOOK_FREQ_CHANGE,  /* System clock changed frequency */
+};
+
+
+struct hook_data {
+	/* Hook processing routine; returns EC error code. */
+	int (*routine)(void);
+	/* Priority; low numbers = higher priority. */
+	int priority;
+};
+
+
+/* Call all the hook routines of a specified type.  If stop_on_error, stops on
+ * the first non-EC_SUCCESS return code.  Returns the first non-EC_SUCCESS
+ * return code, if any, or EC_SUCCESS if all hooks returned EC_SUCCESS. */
+int hook_notify(enum hook_type type, int stop_on_error);
+
+
+/* Register a hook routine.  <hooktype> should be one of enum hook_type.
+ * <routine> should be int routine(void), and should return an error code or
+ * EC_SUCCESS if no error.  <priority> should be between HOOK_PRIO_FIRST and
+ * HOOK_PRIO_LAST, and should be HOOK_PRIO_DEFAULT unless there's a compelling
+ * reason to care about the order in which hooks are called. */
+#define DECLARE_HOOK(hooktype, routine, priority)			\
+	const struct hook_data __hook_##hooktype##_##routine		\
+	__attribute__((section(".rodata." #hooktype)))			\
+	     = {routine, priority}
+
+#endif  /* __CROS_EC_HOOKS_H */
diff --git a/include/hwtimer.h b/include/hwtimer.h
index 5fee466b7c..ae0c634163 100644
--- a/include/hwtimer.h
+++ b/include/hwtimer.h
@@ -5,8 +5,8 @@
 
 /* Hardware timer driver API */
 
-#ifndef __EC_HWTIMER_H
-#define __EC_HWTIMER_H
+#ifndef __CROS_EC_HWTIMER_H
+#define __CROS_EC_HWTIMER_H
 
 /**
  * Programs when the next timer should fire an interrupt.
@@ -30,9 +30,6 @@ uint32_t __hw_clock_source_read(void);
  */
 int __hw_clock_source_init(void);
 
-/* Notifies the module the system clock frequency has changed to <freq>. */
-void hwtimer_clock_changed(int freq);
-
 /**
  * Searches the next deadline and program it in the timer hardware.
  *
@@ -43,4 +40,4 @@ void hwtimer_clock_changed(int freq);
  */
 void process_timers(int overflow);
 
-#endif  /* __EC_HWTIMER_H */
+#endif  /* __CROS_EC_HWTIMER_H */
diff --git a/include/i2c.h b/include/i2c.h
index 22ab18adcf..7543d8cb25 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -13,30 +13,23 @@
 /* Flags for slave address field, in addition to the 8-bit address */
 #define I2C_FLAG_BIG_ENDIAN 0x100  /* 16 byte values are MSB-first */
 
-/* Initializes the module. */
+/* Initialize the module. */
 int i2c_init(void);
 
-/* Notifies the module the system clock frequency has changed to <freq>. */
-void i2c_clock_changed(int freq);
-
-/* Reads a 16-bit register from the slave at 8-bit slave address
- * <slaveaddr>, at the specified 8-bit <offset> in the slave's address
- * space. */
+/* Read a 16-bit register from the slave at 8-bit slave address <slaveaddr>, at
+ * the specified 8-bit <offset> in the slave's address space. */
 int i2c_read16(int port, int slave_addr, int offset, int* data);
 
-/* Writes a 16-bit register to the slave at 8-bit slave address
- * <slaveaddr>, at the specified 8-bit <offset> in the slave's address
- * space. */
+/* Write a 16-bit register to the slave at 8-bit slave address <slaveaddr>, at
+ * the specified 8-bit <offset> in the slave's address space. */
 int i2c_write16(int port, int slave_addr, int offset, int data);
 
-/* Reads an 8-bit register from the slave at 8-bit slave address
- * <slaveaddr>, at the specified 8-bit <offset> in the slave's address
- * space. */
+/* Read an 8-bit register from the slave at 8-bit slave address <slaveaddr>, at
+ * the specified 8-bit <offset> in the slave's address space. */
 int i2c_read8(int port, int slave_addr, int offset, int* data);
 
-/* Writes an 8-bit register to the slave at 8-bit slave address
- * <slaveaddr>, at the specified 8-bit <offset> in the slave's address
- * space. */
+/* Write an 8-bit register to the slave at 8-bit slave address <slaveaddr>, at
+ * the specified 8-bit <offset> in the slave's address space. */
 int i2c_write8(int port, int slave_addr, int offset, int data);
 
 /* Read ascii string using smbus read block protocol.
diff --git a/include/peci.h b/include/peci.h
index 7a98a24991..1ad0d92bad 100644
--- a/include/peci.h
+++ b/include/peci.h
@@ -10,21 +10,16 @@
 
 #include "common.h"
 
-struct temp_sensor_t;
-
-/* Initializes the module. */
+/* Initialize the module. */
 int peci_init(void);
 
-/* Notifies the module the system clock frequency has changed to <freq>. */
-void peci_clock_changed(int freq);
-
-/* Returns the current CPU temperature in degrees K, or -1 if error.
+/* Return the current CPU temperature in degrees K, or -1 if error.
  *
  * Note that the PECI interface is currently a little flaky; if you get an
  * error, retry a bit later. */
 int peci_get_cpu_temp(void);
 
-/* Reads the CPU temperature sensor via PECI.  This interface is for the
+/* Read the CPU temperature sensor via PECI.  This interface is for the
  * temperature sensor module.  Returns the temperature in degrees K, or -1 if
  * error. */
 int peci_temp_sensor_get_val(int idx);
diff --git a/include/watchdog.h b/include/watchdog.h
index 569352bc6a..68ac7b917e 100644
--- a/include/watchdog.h
+++ b/include/watchdog.h
@@ -15,7 +15,4 @@ int watchdog_init(int period_ms);
 /* Reload the watchdog counter */
 void watchdog_reload(void);
 
-/* Notifies the module the system clock frequency has changed to <freq>. */
-void watchdog_clock_changed(int freq);
-
 #endif /* __CROS_EC_WATCHDOG_H */