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>

1 files changed, 88 insertions, 5 deletions

diff --git a/drivers/misc/cros_ec.c b/drivers/misc/cros_ec.c
index 4b6ac6a6c0..ae52561609 100644
--- a/drivers/misc/cros_ec.c
+++ b/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,
 };