mec1322: I2C driver

This adds the driver for MEC1322 I2C controller.

BUG=chrome-os-partner:24107
TEST=Hook up TSU6721 to eval board. Do the following tests:
      - 'i2cscan' and see TSU6721.
      - Read device ID register and get correct value.
      - Add 3 tasks randomly doing I2C read and writes. Check there is
	no error.
BRANCH=None

Change-Id: I465f73fe8177a8df6b56c57e594cd733caea37d4
Signed-off-by: Vic (Chun-Ju) Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/178591
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

5 files changed, 388 insertions, 3 deletions

diff --git a/board/mec1322_evb/board.c b/board/mec1322_evb/board.c
index 73a2a19bb4..ced2c5ab27 100644
--- a/board/mec1322_evb/board.c
+++ b/board/mec1322_evb/board.c
@@ -6,6 +6,7 @@
 
 #include "fan.h"
 #include "gpio.h"
+#include "i2c.h"
 #include "registers.h"
 #include "util.h"
 
@@ -23,9 +24,10 @@ BUILD_ASSERT(ARRAY_SIZE(gpio_list) == GPIO_COUNT);
 
 /* Pins with alternate functions */
 const struct gpio_alt_func gpio_alt_funcs[] = {
-	{GPIO_PORT(16), 0x24, 1, MODULE_UART}, /* UART0 */
-	{GPIO_PORT(3), (1 << 4), 3, MODULE_PWM_FAN},
+	{GPIO_PORT(16), 0x24,     1, MODULE_UART}, /* UART0 */
+	{GPIO_PORT(3),  (1 << 4), 3, MODULE_PWM_FAN},
 	{GPIO_PORT(14), (1 << 0), 3, MODULE_PWM_FAN},
+	{GPIO_PORT(1),  0x60,     2, MODULE_I2C},  /* I2C0 */
 };
 const int gpio_alt_funcs_count = ARRAY_SIZE(gpio_alt_funcs);
 
@@ -40,3 +42,9 @@ const struct fan_t fans[] = {
 	},
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == CONFIG_FANS);
+
+/* I2C ports */
+const struct i2c_port_t i2c_ports[] = {
+	{"port0", 0, 100},
+};
+const unsigned int i2c_ports_used = ARRAY_SIZE(i2c_ports);
diff --git a/chip/mec1322/build.mk b/chip/mec1322/build.mk
index 0f7262b8f9..bbc040a284 100644
--- a/chip/mec1322/build.mk
+++ b/chip/mec1322/build.mk
@@ -14,6 +14,7 @@ CFLAGS_CPU+=-march=armv7e-m -mcpu=cortex-m4
 # Required chip modules
 chip-y=clock.o gpio.o hwtimer.o system.o uart.o jtag.o
 chip-$(CONFIG_FANS)+=fan.o
+chip-$(CONFIG_I2C)+=i2c.o
 chip-$(CONFIG_LPC)+=lpc.o
 chip-$(CONFIG_PWM)+=pwm.o
 chip-$(CONFIG_WATCHDOG)+=watchdog.o
diff --git a/chip/mec1322/config_chip.h b/chip/mec1322/config_chip.h
index e49db95fed..e47f102759 100644
--- a/chip/mec1322/config_chip.h
+++ b/chip/mec1322/config_chip.h
@@ -81,11 +81,11 @@
 /* Optional features present on this chip */
 #if 0
 #define CONFIG_ADC
-#define CONFIG_I2C
 #define CONFIG_PECI
 #define CONFIG_SWITCH
 #define CONFIG_MPU
 #endif
+#define CONFIG_I2C
 #define CONFIG_LPC
 #define CONFIG_FPU
 
diff --git a/chip/mec1322/i2c.c b/chip/mec1322/i2c.c
new file mode 100644
index 0000000000..98dd28e170
--- /dev/null
+++ b/chip/mec1322/i2c.c
@@ -0,0 +1,343 @@
+/* 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 port module for MEC1322 */
+
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "i2c.h"
+#include "registers.h"
+#include "task.h"
+#include "timer.h"
+#include "util.h"
+
+#define CPUTS(outstr) cputs(CC_I2C, outstr)
+#define CPRINTF(format, args...) cprintf(CC_I2C, format, ## args)
+
+#define I2C_CLOCK 16000000 /* 16 MHz */
+
+/* Status */
+#define STS_NBB (1 << 0) /* Bus busy */
+#define STS_LAB (1 << 1) /* Arbitration lost */
+#define STS_LRB (1 << 3) /* Last received bit */
+#define STS_BER (1 << 4) /* Bus error */
+#define STS_PIN (1 << 7) /* Pending interrupt */
+
+/* Control */
+#define CTRL_ACK (1 << 0) /* Acknowledge */
+#define CTRL_STO (1 << 1) /* STOP */
+#define CTRL_STA (1 << 2) /* START */
+#define CTRL_ENI (1 << 3) /* Enable interrupt */
+#define CTRL_ESO (1 << 6) /* Enable serial output */
+#define CTRL_PIN (1 << 7) /* Pending interrupt not */
+
+static task_id_t task_waiting_on_port[I2C_PORT_COUNT];
+
+static void configure_port_speed(int port, int kbps)
+{
+	int min_t_low, min_t_high;
+	int t_low, t_high;
+	const int period = I2C_CLOCK / 1000 / kbps;
+
+	/*
+	 * Refer to NXP UM10204 for minimum timing requirement of T_Low and
+	 * T_High.
+	 * http://www.nxp.com/documents/user_manual/UM10204.pdf
+	 */
+
+	if (kbps > 400) {
+		/* Fast mode plus */
+		min_t_low = I2C_CLOCK * 0.5 / 1000000 - 1; /* 0.5 us */
+		min_t_high = I2C_CLOCK * 0.26 / 1000000 - 1; /* 0.26 us */
+		MEC1322_I2C_DATA_TIM(port) = 0x06060601;
+		MEC1322_I2C_DATA_TIM_2(port) = 0x06;
+	} else if (kbps > 100) {
+		/* Fast mode */
+		min_t_low = I2C_CLOCK * 1.3 / 1000000 - 1; /* 1.3 us */
+		min_t_high = I2C_CLOCK * 0.6 / 1000000 - 1; /* 0.6 us */
+		MEC1322_I2C_DATA_TIM(port) = 0x040a0a01;
+		MEC1322_I2C_DATA_TIM_2(port) = 0x0a;
+	} else {
+		/* Standard mode */
+		min_t_low = I2C_CLOCK * 4.7 / 1000000 - 1; /* 4.7 us */
+		min_t_high = I2C_CLOCK * 4.0 / 1000000 - 1; /* 4.0 us */
+		MEC1322_I2C_DATA_TIM(port) = 0x0c4d5006;
+		MEC1322_I2C_DATA_TIM_2(port) = 0x4d;
+	}
+
+	t_low = MAX(min_t_low + 1, period / 2);
+	t_high = MAX(min_t_high + 1, period - t_low);
+
+	MEC1322_I2C_BUS_CLK(port) = ((t_high & 0xff) << 8) |
+				    (t_low & 0xff);
+}
+
+static void configure_port(int port, int kbps)
+{
+	MEC1322_I2C_CTRL(port) = CTRL_PIN;
+	MEC1322_I2C_OWN_ADDR(port) = 0x0;
+	configure_port_speed(port, kbps);
+	MEC1322_I2C_CTRL(port) = CTRL_PIN | CTRL_ESO | CTRL_ACK | CTRL_ENI;
+	MEC1322_I2C_CONFIG(port) |= 1 << 10; /* ENAB */
+
+	/* Enable interrupt */
+	MEC1322_I2C_CONFIG(port) |= 1 << 29; /* ENIDI */
+	MEC1322_INT_ENABLE(12) |= (1 << port);
+	MEC1322_INT_BLK_EN |= 1 << 12;
+	task_enable_irq(MEC1322_IRQ_I2C_0 + port);
+}
+
+static void reset_port(int port)
+{
+	int i;
+
+	MEC1322_I2C_CONFIG(port) |= 1 << 9;
+	udelay(100);
+	MEC1322_I2C_CONFIG(port) &= ~(1 << 9);
+
+	for (i = 0; i < i2c_ports_used; ++i)
+		if (port == i2c_ports[i].port) {
+			configure_port(i2c_ports[i].port, i2c_ports[i].kbps);
+			break;
+		}
+}
+
+static int wait_for_interrupt(int port, int *event)
+{
+	task_waiting_on_port[port] = task_get_current();
+	task_enable_irq(MEC1322_IRQ_I2C_0 + port);
+	/*
+	 * We want to wait here quietly until the I2C interrupt comes
+	 * along, but we don't want to lose any pending events that
+	 * will be needed by the task that started the I2C transaction
+	 * in the first place. So we save them up and restore them when
+	 * the I2C is either completed or timed out. Refer to the
+	 * implementation of usleep() for a similar situation.
+	 */
+	*event |= (task_wait_event(SECOND) & ~TASK_EVENT_I2C_IDLE);
+	task_waiting_on_port[port] = TASK_ID_INVALID;
+	if (*event & TASK_EVENT_TIMER) {
+		/* Restore any events that we saw while waiting */
+		task_set_event(task_get_current(),
+				(*event & ~TASK_EVENT_TIMER), 0);
+		return EC_ERROR_TIMEOUT;
+	}
+	return EC_SUCCESS;
+}
+
+static int wait_idle(int port)
+{
+	uint8_t sts = MEC1322_I2C_STATUS(port);
+	int rv;
+	int event = 0;
+
+	while (!(sts & STS_NBB)) {
+		rv = wait_for_interrupt(port, &event);
+		if (rv)
+			return rv;
+		sts = MEC1322_I2C_STATUS(port);
+	}
+	/*
+	 * Restore any events that we saw while waiting. TASK_EVENT_TIMER isn't
+	 * one, because we've handled it above.
+	 */
+	task_set_event(task_get_current(), event, 0);
+
+	if (sts & (STS_BER | STS_LAB))
+		return EC_ERROR_UNKNOWN;
+	return EC_SUCCESS;
+}
+
+static int wait_byte_done(int port)
+{
+	uint8_t sts = MEC1322_I2C_STATUS(port);
+	int rv;
+	int event = 0;
+
+	while (sts & STS_PIN) {
+		rv = wait_for_interrupt(port, &event);
+		if (rv)
+			return rv;
+		sts = MEC1322_I2C_STATUS(port);
+	}
+	/*
+	 * Restore any events that we saw while waiting. TASK_EVENT_TIMER isn't
+	 * one, because we've handled it above.
+	 */
+	task_set_event(task_get_current(), event, 0);
+
+	return sts & STS_LRB;
+}
+
+static inline void fill_in_buf(uint8_t *in, int id, uint8_t val)
+{
+	/*
+	 * On MEC1322, first byte read is dummy read (slave addr).
+	 * Throw it away.
+	 */
+	if (id != 0)
+		in[id - 1] = val;
+}
+
+int i2c_xfer(int port, int slave_addr, const uint8_t *out, int out_size,
+	     uint8_t *in, int in_size, int flags)
+{
+	int i;
+	int started = (flags & I2C_XFER_START) ? 0 : 1;
+	uint8_t reg_sts;
+
+	if (out_size == 0 && in_size == 0)
+		return EC_SUCCESS;
+
+	wait_idle(port);
+
+	reg_sts = MEC1322_I2C_STATUS(port);
+	if (!started &&
+	    ((reg_sts & (STS_BER | STS_LAB)) || !(reg_sts & STS_NBB))) {
+		CPRINTF("[%T I2C%d bad status 0x%02x]\n", port, reg_sts);
+
+		/* Bus error, bus busy, or arbitration lost. Reset port. */
+		reset_port(port);
+
+		/*
+		 * We don't know what edges the slave saw, so sleep long enough
+		 * that the slave will see the new start condition below.
+		 */
+		usleep(1000);
+	}
+
+	if (out) {
+		MEC1322_I2C_DATA(port) = (uint8_t)slave_addr;
+
+		/*
+		 * Clock out the slave address. Send START bit if start flag is
+		 * set.
+		 */
+		MEC1322_I2C_CTRL(port) = CTRL_PIN | CTRL_ESO | CTRL_ENI |
+					 CTRL_ACK | (started ? 0 : CTRL_STA);
+		if (!started)
+			started = 1;
+
+		for (i = 0; i < out_size; ++i) {
+			if (wait_byte_done(port))
+				goto err_i2c_xfer;
+			MEC1322_I2C_DATA(port) = out[i];
+		}
+		if (wait_byte_done(port))
+			goto err_i2c_xfer;
+
+		/*
+		 * Send STOP bit if the stop flag is on, and caller
+		 * doesn't expect to receive data.
+		 */
+		if ((flags & I2C_XFER_STOP) && in_size == 0) {
+			MEC1322_I2C_CTRL(port) = CTRL_PIN | CTRL_ESO |
+						 CTRL_STO | CTRL_ACK;
+		}
+	}
+
+	if (in_size) {
+		if (out_size) {
+			/* resend start bit when change direction */
+			MEC1322_I2C_CTRL(port) = CTRL_ESO | CTRL_STA |
+						 CTRL_ACK | CTRL_ENI;
+		}
+
+		MEC1322_I2C_DATA(port) = (uint8_t)slave_addr | 0x01;
+
+		if (!started) {
+			started = 1;
+			/* Clock out slave address with START bit */
+			MEC1322_I2C_CTRL(port) = CTRL_PIN | CTRL_ESO |
+						 CTRL_STA | CTRL_ACK | CTRL_ENI;
+		}
+
+		/* On MEC1322, first byte read is dummy read (slave addr) */
+		in_size++;
+
+		for (i = 0; i < in_size - 2; ++i) {
+			if (wait_byte_done(port))
+				goto err_i2c_xfer;
+			fill_in_buf(in, i, MEC1322_I2C_DATA(port));
+		}
+		if (wait_byte_done(port))
+			goto err_i2c_xfer;
+
+		/*
+		 * De-assert ACK bit before reading the next to last byte,
+		 * so that the last byte is NACK'ed.
+		 */
+		MEC1322_I2C_CTRL(port) = CTRL_ESO | CTRL_ENI;
+		fill_in_buf(in, in_size - 2, MEC1322_I2C_DATA(port));
+		if (wait_byte_done(port))
+			goto err_i2c_xfer;
+
+		/* Send STOP if stop flag is set */
+		MEC1322_I2C_CTRL(port) =
+			CTRL_PIN | CTRL_ESO | CTRL_ACK |
+			((flags & I2C_XFER_STOP) ? CTRL_STO : 0);
+
+		/* Now read the last byte */
+		fill_in_buf(in, in_size - 1, MEC1322_I2C_DATA(port));
+	}
+
+	/* Check for error conditions */
+	if (MEC1322_I2C_STATUS(port) & (STS_LAB | STS_BER))
+		return EC_ERROR_UNKNOWN;
+
+	return EC_SUCCESS;
+err_i2c_xfer:
+	/* Send STOP and return error */
+	MEC1322_I2C_CTRL(port) = CTRL_PIN | CTRL_ESO | CTRL_STO | CTRL_ACK;
+	return EC_ERROR_UNKNOWN;
+}
+
+int i2c_get_line_levels(int port)
+{
+	return (MEC1322_I2C_BB_CTRL(port) >> 5) & 0x3;
+}
+
+static void i2c_init(void)
+{
+	int i;
+
+	/* Configure GPIOs */
+	gpio_config_module(MODULE_I2C, 1);
+
+	for (i = 0; i < i2c_ports_used; ++i)
+		configure_port(i2c_ports[i].port, i2c_ports[i].kbps);
+}
+DECLARE_HOOK(HOOK_INIT, i2c_init, HOOK_PRIO_DEFAULT);
+
+static void handle_interrupt(int port)
+{
+	int id = task_waiting_on_port[port];
+
+	/* Clear the interrupt status */
+	MEC1322_I2C_COMPLETE(port) |= 1 << 29;
+
+	/*
+	 * Write to control register interferes with I2C transaction.
+	 * Instead, let's disable IRQ from the core until the next time
+	 * we want to wait for STS_PIN/STS_NBB.
+	 */
+	task_disable_irq(MEC1322_IRQ_I2C_0 + port);
+
+	/* Wake up the task which was waiting on the I2C interrupt, if any. */
+	if (id != TASK_ID_INVALID)
+		task_set_event(id, TASK_EVENT_I2C_IDLE, 0);
+}
+
+static void i2c0_interrupt(void) { handle_interrupt(0); }
+static void i2c1_interrupt(void) { handle_interrupt(1); }
+static void i2c2_interrupt(void) { handle_interrupt(2); }
+static void i2c3_interrupt(void) { handle_interrupt(3); }
+
+DECLARE_IRQ(MEC1322_IRQ_I2C_0, i2c0_interrupt, 2);
+DECLARE_IRQ(MEC1322_IRQ_I2C_1, i2c1_interrupt, 2);
+DECLARE_IRQ(MEC1322_IRQ_I2C_2, i2c2_interrupt, 2);
+DECLARE_IRQ(MEC1322_IRQ_I2C_3, i2c3_interrupt, 2);
diff --git a/chip/mec1322/registers.h b/chip/mec1322/registers.h
index e1827fbc61..3f9c350c5c 100644
--- a/chip/mec1322/registers.h
+++ b/chip/mec1322/registers.h
@@ -207,6 +207,39 @@ static inline uintptr_t gpio_port_base(int port_id)
 #define MEC1322_FAN_STATUS     REG8(MEC1322_FAN_BASE + 0x11)
 
 
+/* I2C */
+#define MEC1322_I2C0_BASE      0x40001800
+#define MEC1322_I2C1_BASE      0x4000ac00
+#define MEC1322_I2C2_BASE      0x4000b000
+#define MEC1322_I2C3_BASE      0x4000b400
+#define MEC1322_I2C_BASESEP    0x00000400
+#define MEC1322_I2C_ADDR(port, offset) \
+	(offset + (port == 0 ? MEC1322_I2C0_BASE : \
+		   MEC1322_I2C1_BASE + MEC1322_I2C_BASESEP * (port - 1)))
+
+#define MEC1322_I2C_CTRL(port)          REG8(MEC1322_I2C_ADDR(port, 0x0))
+#define MEC1322_I2C_STATUS(port)        REG8(MEC1322_I2C_ADDR(port, 0x0))
+#define MEC1322_I2C_OWN_ADDR(port)      REG16(MEC1322_I2C_ADDR(port, 0x4))
+#define MEC1322_I2C_DATA(port)          REG8(MEC1322_I2C_ADDR(port, 0x8))
+#define MEC1322_I2C_MASTER_CMD(port)    REG32(MEC1322_I2C_ADDR(port, 0xc))
+#define MEC1322_I2C_SLAVE_CMD(port)     REG32(MEC1322_I2C_ADDR(port, 0x10))
+#define MEC1322_I2C_PEC(port)           REG8(MEC1322_I2C_ADDR(port, 0x14))
+#define MEC1322_I2C_DATA_TIM_2(port)    REG8(MEC1322_I2C_ADDR(port, 0x18))
+#define MEC1322_I2C_COMPLETE(port)      REG32(MEC1322_I2C_ADDR(port, 0x20))
+#define MEC1322_I2C_IDLE_SCALE(port)    REG32(MEC1322_I2C_ADDR(port, 0x24))
+#define MEC1322_I2C_CONFIG(port)        REG32(MEC1322_I2C_ADDR(port, 0x28))
+#define MEC1322_I2C_BUS_CLK(port)       REG16(MEC1322_I2C_ADDR(port, 0x2c))
+#define MEC1322_I2C_BLK_ID(port)        REG8(MEC1322_I2C_ADDR(port, 0x30))
+#define MEC1322_I2C_REV(port)           REG8(MEC1322_I2C_ADDR(port, 0x34))
+#define MEC1322_I2C_BB_CTRL(port)       REG8(MEC1322_I2C_ADDR(port, 0x38))
+#define MEC1322_I2C_DATA_TIM(port)      REG32(MEC1322_I2C_ADDR(port, 0x40))
+#define MEC1322_I2C_TOUT_SCALE(port)    REG32(MEC1322_I2C_ADDR(port, 0x44))
+#define MEC1322_I2C_SLAVE_TX_BUF(port)  REG8(MEC1322_I2C_ADDR(port, 0x48))
+#define MEC1322_I2C_SLAVE_RX_BUF(port)  REG8(MEC1322_I2C_ADDR(port, 0x4c))
+#define MEC1322_I2C_MASTER_TX_BUF(port) REG8(MEC1322_I2C_ADDR(port, 0x50))
+#define MEC1322_I2C_MASTER_RX_BUF(port) REG8(MEC1322_I2C_ADDR(port, 0x54))
+
+
 /* IRQ Numbers */
 #define MEC1322_IRQ_I2C_0        0
 #define MEC1322_IRQ_I2C_1        1