ratp: implement i2c read/write support

Introduce two new RATP commands that allow running i2c read/write
operations, very similar in format to the already existing md/mw
RATP commands.

The messages are defined with a fixed 16-bit long register field, but
it will only be treated as a 16-bit address if I2C_FLAG_WIDE_ADDRESS
is set in the message flags field. If this flag is unset, the start
register address is assumed 8-bit long.

If the message includes the I2C_FLAG_MASTER_MODE flag, the start
register field is ignored and a i2c master send/receive operation is
performed.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 292 insertions, 0 deletions

diff --git a/common/ratp/Kconfig b/common/ratp/Kconfig
index 93ff75d64d..4b28d5f9f7 100644
--- a/common/ratp/Kconfig
+++ b/common/ratp/Kconfig
@@ -12,3 +12,10 @@ config CONSOLE_RATP
 	  this option adds a machine readable interface for controlling barebox.
 	  Say yes here if you want to control barebox from a remote host.
 
+config RATP_CMD_I2C
+	bool
+	depends on RATP
+	depends on I2C
+	prompt "RATP i2c support"
+	help
+	  This option adds support for i2c read/write commands via RATP.
\ No newline at end of file
diff --git a/common/ratp/Makefile b/common/ratp/Makefile
index 2c6d674f61..b83c48327a 100644
--- a/common/ratp/Makefile
+++ b/common/ratp/Makefile
@@ -4,3 +4,4 @@ obj-y += getenv.o
 obj-y += md.o
 obj-y += mw.o
 obj-y += reset.o
+obj-$(CONFIG_RATP_CMD_I2C) += i2c.o
diff --git a/common/ratp/i2c.c b/common/ratp/i2c.c
new file mode 100644
index 0000000000..07097c7f4b
--- /dev/null
+++ b/common/ratp/i2c.c
@@ -0,0 +1,284 @@
+/*
+ * Copyright (c) 2018 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
+ * Copyright (c) 2018 Zodiac Inflight Innovations
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#define pr_fmt(fmt) "barebox-ratp: i2c: " fmt
+
+#include <common.h>
+#include <ratp_bb.h>
+#include <init.h>
+#include <driver.h>
+#include <malloc.h>
+#include <errno.h>
+#include <i2c/i2c.h>
+
+/* NOTE:
+ *  - Fixed-size fields (e.g. integers) are given just after the header.
+ *  - Variable-length fields are stored inside the buffer[] and their position
+ *    within the buffer[] and their size are given as fixed-sized fields after
+ *    the header.
+ *  The message may be extended at any time keeping backwards compatibility,
+ *  as the position of the buffer[] is given by the buffer_offset field. i.e.
+ *  increasing the buffer_offset field we can extend the fixed-sized section
+ *  to add more fields.
+ */
+
+#define I2C_FLAG_WIDE_ADDRESS BIT(0)
+#define I2C_FLAG_MASTER_MODE  BIT(1)
+
+struct ratp_bb_i2c_read_request {
+	struct ratp_bb header;
+	uint16_t buffer_offset;
+	uint8_t  bus;
+	uint8_t  addr;
+	uint16_t reg;
+	uint8_t  flags;
+	uint16_t size;
+	uint8_t  buffer[];
+} __packed;
+
+struct ratp_bb_i2c_read_response {
+	struct ratp_bb header;
+	uint16_t buffer_offset;
+	uint32_t errno;
+	uint16_t data_size;
+	uint16_t data_offset;
+	uint8_t  buffer[];
+} __packed;
+
+struct ratp_bb_i2c_write_request {
+	struct ratp_bb header;
+	uint16_t buffer_offset;
+	uint8_t  bus;
+	uint8_t  addr;
+	uint16_t reg;
+	uint8_t  flags;
+	uint16_t data_size;
+	uint16_t data_offset;
+	uint8_t  buffer[];
+} __packed;
+
+struct ratp_bb_i2c_write_response {
+	struct ratp_bb header;
+	uint16_t buffer_offset;
+	uint32_t errno;
+	uint16_t written;
+	uint8_t  buffer[];
+} __packed;
+
+static int ratp_cmd_i2c_read(const struct ratp_bb *req, int req_len,
+			     struct ratp_bb **rsp, int *rsp_len)
+{
+	struct ratp_bb_i2c_read_request *i2c_read_req = (struct ratp_bb_i2c_read_request *)req;
+	struct ratp_bb_i2c_read_response *i2c_read_rsp;
+	struct i2c_adapter *adapter;
+	struct i2c_client client;
+	uint16_t buffer_offset;
+	int i2c_read_rsp_len;
+	uint16_t reg;
+	uint16_t size;
+	uint32_t wide = 0;
+	int ret = 0;
+
+	/* At least message header should be valid */
+	if (req_len < sizeof(*i2c_read_req)) {
+		pr_err("read ignored: size mismatch (%d < %zu)\n",
+		       req_len, sizeof(*i2c_read_req));
+		ret = -EINVAL;
+		goto out_rsp;
+	}
+
+	/* We don't require any buffer here, but just validate buffer position and size */
+	buffer_offset = be16_to_cpu(i2c_read_req->buffer_offset);
+	if (buffer_offset != req_len) {
+		pr_err("read ignored: invalid buffer offset (%hu != %d)\n",
+		       buffer_offset, req_len);
+		ret = -EINVAL;
+		goto out_rsp;
+	}
+
+	reg  = be16_to_cpu(i2c_read_req->reg);
+	size = be16_to_cpu(i2c_read_req->size);
+	if (i2c_read_req->flags & I2C_FLAG_WIDE_ADDRESS)
+		wide = I2C_ADDR_16_BIT;
+
+out_rsp:
+	/* Avoid reading anything on error */
+	if (ret != 0)
+		size = 0;
+
+	i2c_read_rsp_len = sizeof(*i2c_read_rsp) + size;
+	i2c_read_rsp = xzalloc(i2c_read_rsp_len);
+	i2c_read_rsp->header.type = cpu_to_be16(BB_RATP_TYPE_I2C_READ_RETURN);
+	i2c_read_rsp->buffer_offset = cpu_to_be16(sizeof(*i2c_read_rsp));
+	i2c_read_rsp->data_offset = 0;
+
+	/* Don't read anything on error or if 0 bytes were requested */
+	if (size > 0) {
+		adapter = i2c_get_adapter(i2c_read_req->bus);
+		if (!adapter) {
+			pr_err("read ignored: i2c bus %u not found\n", i2c_read_req->bus);
+			ret = -ENODEV;
+			goto out;
+		}
+
+		client.adapter = adapter;
+		client.addr = i2c_read_req->addr;
+
+		if (i2c_read_req->flags & I2C_FLAG_MASTER_MODE) {
+			ret = i2c_master_recv(&client, i2c_read_rsp->buffer, size);
+		} else {
+			ret = i2c_read_reg(&client, reg | wide, i2c_read_rsp->buffer, size);
+		}
+		if (ret != size) {
+			pr_err("read ignored: not all bytes read (%u < %u)\n", ret, size);
+			ret = -EIO;
+			goto out;
+		}
+		ret = 0;
+	}
+
+out:
+	if (ret != 0) {
+		i2c_read_rsp->data_size = 0;
+		i2c_read_rsp->errno = cpu_to_be32(ret);
+		i2c_read_rsp_len = sizeof(*i2c_read_rsp);
+	} else {
+		i2c_read_rsp->data_size = cpu_to_be16(size);
+		i2c_read_rsp->errno = 0;
+	}
+
+	*rsp = (struct ratp_bb *)i2c_read_rsp;
+	*rsp_len = i2c_read_rsp_len;
+
+	return ret;
+}
+
+BAREBOX_RATP_CMD_START(I2C_READ)
+	.request_id = BB_RATP_TYPE_I2C_READ,
+	.response_id = BB_RATP_TYPE_I2C_READ_RETURN,
+	.cmd = ratp_cmd_i2c_read
+BAREBOX_RATP_CMD_END
+
+
+static int ratp_cmd_i2c_write(const struct ratp_bb *req, int req_len,
+			     struct ratp_bb **rsp, int *rsp_len)
+{
+	struct ratp_bb_i2c_write_request *i2c_write_req = (struct ratp_bb_i2c_write_request *)req;
+	struct ratp_bb_i2c_write_response *i2c_write_rsp;
+	struct i2c_adapter *adapter;
+	struct i2c_client client;
+	uint8_t *buffer;
+	uint16_t buffer_offset;
+	uint16_t buffer_size;
+	uint16_t reg;
+	uint16_t data_offset;
+	uint16_t data_size;
+	uint32_t wide = 0;
+	int ret = 0;
+	int written = 0;
+
+	/* At least message header should be valid */
+	if (req_len < sizeof(*i2c_write_req)) {
+		pr_err("write ignored: size mismatch (%d < %zu)\n",
+		       req_len, sizeof(*i2c_write_req));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Validate buffer position and size */
+	buffer_offset = be16_to_cpu(i2c_write_req->buffer_offset);
+	if (req_len < buffer_offset) {
+		pr_err("write ignored: invalid buffer offset (%d < %hu)\n",
+		       req_len, buffer_offset);
+		ret = -EINVAL;
+		goto out;
+	}
+	buffer_size = req_len - buffer_offset;
+	buffer = ((uint8_t *)i2c_write_req) + buffer_offset;
+
+	/* Validate data position and size */
+	data_offset = be16_to_cpu(i2c_write_req->data_offset);
+	if (data_offset != 0) {
+		pr_err("write ignored: invalid data offset\n");
+		ret = -EINVAL;
+		goto out;
+	}
+	data_size = be16_to_cpu(i2c_write_req->data_size);
+	if (!data_size) {
+		/* Success */
+		goto out;
+	}
+
+	/* Validate buffer size */
+	if (buffer_size < data_size) {
+		pr_err("write ignored: size mismatch (%d < %hu): data not fully given\n",
+		       buffer_size, data_size);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	reg  = be16_to_cpu(i2c_write_req->reg);
+	if (i2c_write_req->flags & I2C_FLAG_WIDE_ADDRESS)
+		wide = I2C_ADDR_16_BIT;
+
+	adapter = i2c_get_adapter(i2c_write_req->bus);
+	if (!adapter) {
+		pr_err("write ignored: i2c bus %u not found\n", i2c_write_req->bus);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	client.adapter = adapter;
+	client.addr = i2c_write_req->addr;
+
+	if (i2c_write_req->flags & I2C_FLAG_MASTER_MODE) {
+		written = i2c_master_send(&client, &buffer[data_offset], data_size);
+	} else {
+		written = i2c_write_reg(&client, reg | wide, &buffer[data_offset], data_size);
+	}
+
+	if (written != data_size) {
+		pr_err("write ignored: not all bytes written (%u < %u)\n", ret, data_size);
+		ret = -EIO;
+		goto out;
+	}
+
+out:
+	i2c_write_rsp = xzalloc(sizeof(*i2c_write_rsp));
+	i2c_write_rsp->header.type = cpu_to_be16(BB_RATP_TYPE_I2C_WRITE_RETURN);
+	i2c_write_rsp->buffer_offset = cpu_to_be16(sizeof(*i2c_write_rsp));  /* n/a */
+
+	if (ret != 0) {
+		i2c_write_rsp->written = 0;
+		i2c_write_rsp->errno = cpu_to_be32(ret);
+	} else {
+		i2c_write_rsp->written = cpu_to_be16((uint16_t)written);
+		i2c_write_rsp->errno = 0;
+	}
+
+	*rsp = (struct ratp_bb *)i2c_write_rsp;
+	*rsp_len = sizeof(*i2c_write_rsp);
+
+	return ret;
+}
+
+BAREBOX_RATP_CMD_START(I2C_WRITE)
+	.request_id = BB_RATP_TYPE_I2C_WRITE,
+	.response_id = BB_RATP_TYPE_I2C_WRITE_RETURN,
+	.cmd = ratp_cmd_i2c_write
+BAREBOX_RATP_CMD_END