dm: cros_ec: Convert the I2C tunnel code to use driver model

The Chrome OS EC supports tunnelling through to an I2C bus on the EC. This
currently uses a copy of the I2C command code and a special 'crosec'
sub-command.

With driver model we can define an I2C bus which tunnels through to the EC,
and use the normal 'i2c' command to access it. This simplifies the code and
removes some duplication.

Add an I2C driver which tunnels through to the EC. Adjust the EC code to
support binding child devices so that it can be set up. Adjust the existing
I2C xfer function to fit driver model better.

For now the old code remains to allow things to still work. It will be
removed in a later patch once the new flow is fully enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>

configs/peach-pi_defconfig

@@ -12,3 +12,5 @@ CONFIG_CROS_EC_SPI=y
 CONFIG_CROS_EC_KEYB=y
 CONFIG_USB=y
 CONFIG_DM_USB=y
+CONFIG_I2C_MUX=y
+CONFIG_I2C_CROS_EC_TUNNEL=y

configs/peach-pit_defconfig

@@ -12,3 +12,5 @@ CONFIG_CROS_EC_SPI=y
 CONFIG_CROS_EC_KEYB=y
 CONFIG_USB=y
 CONFIG_DM_USB=y
+CONFIG_I2C_MUX=y
+CONFIG_I2C_CROS_EC_TUNNEL=y

drivers/i2c/Kconfig

@@ -19,6 +19,17 @@ config DM_I2C_COMPAT
 	  to convert all code for a board in a single commit. It should not
 	  be enabled for any board in an official release.
 
+config I2C_CROS_EC_TUNNEL
+	tristate "Chrome OS EC tunnel I2C bus"
+	depends on CROS_EC
+	help
+	  This provides an I2C bus that will tunnel i2c commands through to
+	  the other side of the Chrome OS EC to the I2C bus connected there.
+	  This will work whatever the interface used to talk to the EC (SPI,
+	  I2C or LPC). Some Chromebooks use this when the hardware design
+	  does not allow direct access to the main PMIC from the AP.
+
+
 config DM_I2C_GPIO
 	bool "Enable Driver Model for software emulated I2C bus driver"
 	depends on DM_I2C && DM_GPIO

drivers/i2c/Makefile

@@ -7,6 +7,7 @@
 obj-$(CONFIG_DM_I2C) += i2c-uclass.o
 obj-$(CONFIG_DM_I2C_COMPAT) += i2c-uclass-compat.o
 obj-$(CONFIG_DM_I2C_GPIO) += i2c-gpio.o
+obj-$(CONFIG_I2C_CROS_EC_TUNNEL) += cros_ec_tunnel.o
 
 obj-$(CONFIG_SYS_I2C_ADI) += adi_i2c.o
 obj-$(CONFIG_I2C_MV) += mv_i2c.o

drivers/i2c/cros_ec_tunnel.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <cros_ec.h>
+#include <errno.h>
+#include <i2c.h>
+
+static int cros_ec_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
+{
+	return 0;
+}
+
+static int cros_ec_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
+			    int nmsgs)
+{
+	return cros_ec_i2c_tunnel(dev->parent, msg, nmsgs);
+}
+
+static const struct dm_i2c_ops cros_ec_i2c_ops = {
+	.xfer		= cros_ec_i2c_xfer,
+	.set_bus_speed	= cros_ec_i2c_set_bus_speed,
+};
+
+static const struct udevice_id cros_ec_i2c_ids[] = {
+	{ .compatible = "google,cros-ec-i2c-tunnel" },
+	{ }
+};
+
+U_BOOT_DRIVER(cros_ec_tunnel) = {
+	.name	= "cros_ec_tunnel",
+	.id	= UCLASS_I2C,
+	.of_match = cros_ec_i2c_ids,
+	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
+	.ops	= &cros_ec_i2c_ops,
+};

drivers/misc/cros_ec.c

@@ -26,6 +26,7 @@
 #include <asm/io.h>
 #include <asm-generic/gpio.h>
 #include <dm/device-internal.h>
+#include <dm/root.h>
 #include <dm/uclass-internal.h>
 
 #ifdef DEBUG_TRACE
@@ -1053,8 +1054,8 @@ int cros_ec_decode_ec_flash(const void *blob, int node,
 	return 0;
 }
 
-int cros_ec_i2c_xfer(struct cros_ec_dev *dev, uchar chip, uint addr,
-		     int alen, uchar *buffer, int len, int is_read)
+int cros_ec_i2c_xfer_old(struct cros_ec_dev *dev, uchar chip, uint addr,
+			 int alen, uchar *buffer, int len, int is_read)
 {
 	union {
 		struct ec_params_i2c_passthru p;
@@ -1134,6 +1135,81 @@ int cros_ec_i2c_xfer(struct cros_ec_dev *dev, uchar chip, uint addr,
 	return 0;
 }
 
+int cros_ec_i2c_tunnel(struct udevice *dev, struct i2c_msg *in, int nmsgs)
+{
+	struct cros_ec_dev *cdev = dev_get_uclass_priv(dev);
+	union {
+		struct ec_params_i2c_passthru p;
+		uint8_t outbuf[EC_PROTO2_MAX_PARAM_SIZE];
+	} params;
+	union {
+		struct ec_response_i2c_passthru r;
+		uint8_t inbuf[EC_PROTO2_MAX_PARAM_SIZE];
+	} response;
+	struct ec_params_i2c_passthru *p = &params.p;
+	struct ec_response_i2c_passthru *r = &response.r;
+	struct ec_params_i2c_passthru_msg *msg;
+	uint8_t *pdata, *read_ptr = NULL;
+	int read_len;
+	int size;
+	int rv;
+	int i;
+
+	p->port = 0;
+
+	p->num_msgs = nmsgs;
+	size = sizeof(*p) + p->num_msgs * sizeof(*msg);
+
+	/* Create a message to write the register address and optional data */
+	pdata = (uint8_t *)p + size;
+
+	read_len = 0;
+	for (i = 0, msg = p->msg; i < nmsgs; i++, msg++, in++) {
+		bool is_read = in->flags & I2C_M_RD;
+
+		msg->addr_flags = in->addr;
+		msg->len = in->len;
+		if (is_read) {
+			msg->addr_flags |= EC_I2C_FLAG_READ;
+			read_len += in->len;
+			read_ptr = in->buf;
+			if (sizeof(*r) + read_len > sizeof(response)) {
+				puts("Read length too big for buffer\n");
+				return -1;
+			}
+		} else {
+			if (pdata - (uint8_t *)p + in->len > sizeof(params)) {
+				puts("Params too large for buffer\n");
+				return -1;
+			}
+			memcpy(pdata, in->buf, in->len);
+			pdata += in->len;
+		}
+	}
+
+	rv = ec_command(cdev, EC_CMD_I2C_PASSTHRU, 0, p, pdata - (uint8_t *)p,
+			r, sizeof(*r) + read_len);
+	if (rv < 0)
+		return rv;
+
+	/* Parse response */
+	if (r->i2c_status & EC_I2C_STATUS_ERROR) {
+		printf("Transfer failed with status=0x%x\n", r->i2c_status);
+		return -1;
+	}
+
+	if (rv < sizeof(*r) + read_len) {
+		puts("Truncated read response\n");
+		return -1;
+	}
+
+	/* We only support a single read message for each transfer */
+	if (read_len)
+		memcpy(read_ptr, r->data, read_len);
+
+	return 0;
+}
+
 #ifdef CONFIG_CMD_CROS_EC
 
 /**
@@ -1267,8 +1343,8 @@ static int cros_ec_i2c_md(struct cros_ec_dev *dev, int flag, int argc,
 
 		linebytes = (nbytes > DISP_LINE_LEN) ? DISP_LINE_LEN : nbytes;
 
-		if (cros_ec_i2c_xfer(dev, chip, addr, alen, linebuf, linebytes,
-				     1))
+		if (cros_ec_i2c_xfer_old(dev, chip, addr, alen, linebuf,
+					 linebytes, 1))
 			puts("Error reading the chip.\n");
 		else {
 			printf("%04x:", addr);
@@ -1333,7 +1409,7 @@ static int cros_ec_i2c_mw(struct cros_ec_dev *dev, int flag, int argc,
 		count = 1;
 
 	while (count-- > 0) {
-		if (cros_ec_i2c_xfer(dev, chip, addr++, alen, &byte, 1, 0))
+		if (cros_ec_i2c_xfer_old(dev, chip, addr++, alen, &byte, 1, 0))
 			puts("Error writing the chip.\n");
 		/*
 		 * Wait for the write to complete.  The write can take
@@ -1633,6 +1709,12 @@ static int do_cros_ec(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	return ret;
 }
 
+int cros_ec_post_bind(struct udevice *dev)
+{
+	/* Scan for available EC devices (e.g. I2C tunnel) */
+	return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
+}
+
 U_BOOT_CMD(
 	crosec,	6,	1,	do_cros_ec,
 	"CROS-EC utility command",
@@ -1661,4 +1743,5 @@ UCLASS_DRIVER(cros_ec) = {
 	.id		= UCLASS_CROS_EC,
 	.name		= "cros_ec",
 	.per_device_auto_alloc_size = sizeof(struct cros_ec_dev),
+	.post_bind	= cros_ec_post_bind,
 };

drivers/power/pmic/pmic_tps65090_ec.c

@@ -56,8 +56,8 @@ enum {
  */
 static int tps65090_read(u32 reg, u8 *val)
 {
-	return cros_ec_i2c_xfer(config.dev, TPS65090_ADDR, reg, 1,
-				val, 1, true);
+	return cros_ec_i2c_xfer_old(config.dev, TPS65090_ADDR, reg, 1,
+				    val, 1, true);
 }
 
 /**
@@ -69,8 +69,8 @@ static int tps65090_read(u32 reg, u8 *val)
  */
 static int tps65090_write(u32 reg, u8 val)
 {
-	return cros_ec_i2c_xfer(config.dev, TPS65090_ADDR, reg, 1,
-				&val, 1, false);
+	return cros_ec_i2c_xfer_old(config.dev, TPS65090_ADDR, reg, 1,
+				    &val, 1, false);
 }
 
 /**

include/cros_ec.h

@@ -390,6 +390,16 @@ int cros_ec_decode_ec_flash(const void *blob, int node,
  */
 void cros_ec_check_keyboard(struct cros_ec_dev *dev);
 
+struct i2c_msg;
+/*
+ * Tunnel an I2C transfer to the EC
+ *
+ * @param dev		CROS-EC device
+ * @param msg		List of messages to transfer
+ * @param nmsgs		Number of messages to transfer
+ */
+int cros_ec_i2c_tunnel(struct udevice *dev, struct i2c_msg *msg, int nmsgs);
+
 /*
  * Tunnel an I2C transfer to the EC
  *
@@ -401,7 +411,7 @@ void cros_ec_check_keyboard(struct cros_ec_dev *dev);
  * @param len		Length of buffer
  * @param is_read	1 if this is a read, 0 if this is a write
  */
-int cros_ec_i2c_xfer(struct cros_ec_dev *dev, uchar chip, uint addr,
-		     int alen, uchar *buffer, int len, int is_read);
+int cros_ec_i2c_xfer_old(struct cros_ec_dev *dev, uchar chip, uint addr,
+			 int alen, uchar *buffer, int len, int is_read);
 
 #endif