[PATCH] mfd: cros-ec: Add cros_ec_readmem() helpers for I2C/SPI based ECs

[Moritz Fischer]

Add cros_ec_readmem() based helpers for I2C/SPI based ECs.
Unlike the LPC based ECs the I2C/SPI based ones cannot just directly
read the mapped region.

Signed-off-by: Moritz Fischer <mdf@xxxxxxxxxx>
---

Hi Lee,

I'm currently reworking my patchset for the cros-ec hwmon,
and as part of the feedback there Guenter had pointed out that I should use
the cmd_readmem() callbacks. Since they don't exist for the I2C / SPI ECs
I'll send this patch ahead, while working on my hwmon patchset.

Thanks,

Moritz
---
 drivers/mfd/cros_ec.c     | 39 +++++++++++++++++++++++++++++++++++++++
 drivers/mfd/cros_ec.h     | 29 +++++++++++++++++++++++++++++
 drivers/mfd/cros_ec_i2c.c |  3 +++
 drivers/mfd/cros_ec_spi.c |  2 ++
 4 files changed, 73 insertions(+)
 create mode 100644 drivers/mfd/cros_ec.h

diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index d4a407e..2121cd5 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -2,6 +2,7 @@
  * ChromeOS EC multi-function device
  *
  * Copyright (C) 2012 Google, Inc
+ * Copyright (C) 2017 National Instruments Corp
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -265,5 +266,43 @@ EXPORT_SYMBOL(cros_ec_resume);
 
 #endif
 
+int cros_ec_readmem(struct cros_ec_device *ec, unsigned int offset,
+			   unsigned int bytes, void *dest)
+{
+	int ret;
+	struct ec_params_read_memmap *params;
+	struct cros_ec_command *msg;
+
+	if (offset >= EC_MEMMAP_SIZE - bytes)
+		return -EINVAL;
+
+	msg = kzalloc(sizeof(*msg) + max(sizeof(*params), bytes), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	msg->version = 0;
+	msg->command = EC_CMD_READ_MEMMAP;
+	msg->insize = bytes;
+	msg->outsize = sizeof(*params);
+
+	params = (struct ec_params_read_memmap *)msg->data;
+	params->offset = offset;
+	params->size = bytes;
+
+	ret = cros_ec_cmd_xfer_status(ec, msg);
+	if (ret < 0) {
+		dev_warn(ec->dev, "cannot read mapped reg: %d/%d\n",
+			 ret, msg->result);
+		goto out_free;
+	}
+
+	memcpy(dest, msg->data, bytes);
+
+out_free:
+	kfree(msg);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cros_ec_readmem);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("ChromeOS EC core driver");
diff --git a/drivers/mfd/cros_ec.h b/drivers/mfd/cros_ec.h
new file mode 100644
index 0000000..09e83e6
--- /dev/null
+++ b/drivers/mfd/cros_ec.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2017 National Instruments Corp
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#ifndef MFD_CROS_EC_H
+#define MFD_CROS_EC_H
+
+/**
+ * cros_ec_readmem - Read mapped memory in the ChromeOS EC
+ *
+ * @ec: Device to read from
+ * @offset: Offset to read within the mapped region
+ * @bytes: number of bytes to read
+ * @data: Return data
+ * @return: 0 if Ok, -ve on error
+ */
+int cros_ec_readmem(struct cros_ec_device *ec, unsigned int offset,
+		    unsigned int bytes, void *dest);
+
+#endif /* MFD_CROS_EC_H */
diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
index 9f70de1..012f949 100644
--- a/drivers/mfd/cros_ec_i2c.c
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -23,6 +23,8 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
+#include "cros_ec.h"
+
 /**
  * Request format for protocol v3
  * byte 0	0xda (EC_COMMAND_PROTOCOL_3)
@@ -302,6 +304,7 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
 	ec_dev->irq = client->irq;
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
+	ec_dev->cmd_readmem = cros_ec_readmem;
 	ec_dev->phys_name = client->adapter->name;
 	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
 			   sizeof(struct ec_response_get_protocol_info);
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index c971407..8f90bd6 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 
+#include "cros_ec.h"
 
 /* The header byte, which follows the preamble */
 #define EC_MSG_HEADER			0xec
@@ -661,6 +662,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
 	ec_dev->irq = spi->irq;
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
+	ec_dev->cmd_readmem = cros_ec_readmem;
 	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
 	ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
 			   sizeof(struct ec_host_response) +
-- 
2.7.4