[PATCH v12 15/19] input: cyapa: add gen3 trackpad device read firmware image function support

[Dudley Du <dudley.dulixin@gmail.com>]

Add read firmware image function supported for gen3 trackpad device,
it can be used through debugfs read_fw interface.
TEST=test on Chromebooks.

Signed-off-by: Dudley Du <dudley.dulixin@gmail.com>
---
 drivers/input/mouse/cyapa_gen3.c | 67 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/drivers/input/mouse/cyapa_gen3.c b/drivers/input/mouse/cyapa_gen3.c
index 640b916..dd1313e 100644
--- a/drivers/input/mouse/cyapa_gen3.c
+++ b/drivers/input/mouse/cyapa_gen3.c
@@ -708,6 +708,36 @@ static int cyapa_gen3_write_fw_block(struct cyapa *cyapa,
 	return ret;
 }
 
+/*
+ * A firmware block read command reads 16 bytes of data from flash starting
+ * from a given address.  The 12-byte block read command has the format:
+ *   <0xff> <CMD> <Key> <Addr>
+ *
+ *  <0xff>  - every command starts with 0xff
+ *  <CMD>   - the read command value is 0x3c
+ *  <Key>   - read commands include an 8-byte key: { 00 01 02 03 04 05 06 07 }
+ *  <Addr>  - Memory address (16-bit, big-endian)
+ *
+ * The command is followed by an i2c block read to read the 16 bytes of data.
+ */
+static int cyapa_gen3_read_fw_bytes(struct cyapa *cyapa, u16 addr, u8 *data)
+{
+	u8 cmd[] = { 0xff, 0x3c, 0x00, 0x01, 0x02, 0x03, 0x04,
+		0x05, 0x06, 0x07, addr >> 8, addr };
+	int ret, error;
+
+	error = cyapa_gen3_write_buffer(cyapa, cmd, sizeof(cmd));
+	if (error)
+		return error;
+
+	/* Read data buffer starting from offset 16 */
+	ret = cyapa_i2c_reg_read_block(cyapa, 16, CYAPA_FW_READ_SIZE, data);
+	if (ret != CYAPA_FW_READ_SIZE)
+		return (ret < 0) ? ret : -EIO;
+
+	return 0;
+}
+
 static int cyapa_gen3_write_blocks(struct cyapa *cyapa,
 		size_t start_block, size_t block_count,
 		const u8 *image_data)
@@ -754,6 +784,41 @@ static int cyapa_gen3_do_fw_update(struct cyapa *cyapa,
 	return 0;
 }
 
+/*
+ * Read the entire firmware image into ->fw_image.
+ * If the ->fw_image has already been allocated, then this function
+ * doesn't do anything and just returns 0.
+ * If an error occurs while reading the image, ->fw_image is freed, and
+ * the error is returned.
+ *
+ * The firmware is a fixed size (CYAPA_FW_SIZE), and is read out in
+ * fixed length (CYAPA_FW_READ_SIZE) chunks.
+ */
+static int cyapa_gen3_read_fw(struct cyapa *cyapa)
+{
+	int error;
+	int addr;
+
+	error = cyapa_gen3_bl_enter(cyapa);
+	if (error)
+		return error;
+
+	cyapa->fw_image = cyapa->fw_image ? cyapa->fw_image :
+		devm_kzalloc(&cyapa->client->dev, CYAPA_FW_SIZE, GFP_KERNEL);
+	if (!cyapa->fw_image)
+		return -ENOMEM;
+
+	for (addr = 0; addr < CYAPA_FW_SIZE; addr += CYAPA_FW_READ_SIZE) {
+		error = cyapa_gen3_read_fw_bytes(cyapa,
+			CYAPA_FW_HDR_START + addr, &cyapa->fw_image[addr]);
+		if (error)
+			return error;
+	}
+
+	cyapa->fw_image_size = CYAPA_FW_SIZE;
+	return 0;
+}
+
 static ssize_t cyapa_gen3_do_calibrate(struct device *dev,
 				     struct device_attribute *attr,
 				     const char *buf, size_t count)
@@ -1195,6 +1260,8 @@ const struct cyapa_dev_ops cyapa_gen3_ops = {
 	.show_baseline = cyapa_gen3_show_baseline,
 	.calibrate_store = cyapa_gen3_do_calibrate,
 
+	.read_fw = cyapa_gen3_read_fw,
+
 	.state_parse = cyapa_gen3_state_parse,
 	.operational_check = cyapa_gen3_do_operational_check,
 
-- 
1.9.1