drm/dsi: Implement generic read and write commands

Implement generic read and write commands. Selection of the proper data
type for packets is done automatically based on the number of parameters
or payload length.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -356,6 +356,95 @@ int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
 }
 EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
 
+/**
+ * mipi_dsi_generic_write() - transmit data using a generic write packet
+ * @dsi: DSI peripheral device
+ * @payload: buffer containing the payload
+ * @size: size of payload buffer
+ *
+ * This function will automatically choose the right data type depending on
+ * the payload length.
+ *
+ * Return: The number of bytes transmitted on success or a negative error code
+ * on failure.
+ */
+ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
+			       size_t size)
+{
+	struct mipi_dsi_msg msg = {
+		.channel = dsi->channel,
+		.tx_buf = payload,
+		.tx_len = size
+	};
+
+	switch (size) {
+	case 0:
+		msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM;
+		break;
+
+	case 1:
+		msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM;
+		break;
+
+	case 2:
+		msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM;
+		break;
+
+	default:
+		msg.type = MIPI_DSI_GENERIC_LONG_WRITE;
+		break;
+	}
+
+	return mipi_dsi_device_transfer(dsi, &msg);
+}
+EXPORT_SYMBOL(mipi_dsi_generic_write);
+
+/**
+ * mipi_dsi_generic_read() - receive data using a generic read packet
+ * @dsi: DSI peripheral device
+ * @params: buffer containing the request parameters
+ * @num_params: number of request parameters
+ * @data: buffer in which to return the received data
+ * @size: size of receive buffer
+ *
+ * This function will automatically choose the right data type depending on
+ * the number of parameters passed in.
+ *
+ * Return: The number of bytes successfully read or a negative error code on
+ * failure.
+ */
+ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params,
+			      size_t num_params, void *data, size_t size)
+{
+	struct mipi_dsi_msg msg = {
+		.channel = dsi->channel,
+		.tx_len = num_params,
+		.tx_buf = params,
+		.rx_len = size,
+		.rx_buf = data
+	};
+
+	switch (num_params) {
+	case 0:
+		msg.type = MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM;
+		break;
+
+	case 1:
+		msg.type = MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM;
+		break;
+
+	case 2:
+		msg.type = MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return mipi_dsi_device_transfer(dsi, &msg);
+}
+EXPORT_SYMBOL(mipi_dsi_generic_read);
+
 /**
  * mipi_dsi_dcs_write_buffer() - transmit a DCS command with payload
  * @dsi: DSI peripheral device

include/drm/drm_mipi_dsi.h

@@ -155,6 +155,12 @@ int mipi_dsi_attach(struct mipi_dsi_device *dsi);
 int mipi_dsi_detach(struct mipi_dsi_device *dsi);
 int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
 					    u16 value);
+
+ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
+			       size_t size);
+ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params,
+			      size_t num_params, void *data, size_t size);
+
 ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
 				  const void *data, size_t len);
 ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,