[PATCH v4] HID: intel-ish-hid: ISH firmware loader client driver

[Rushikesh S Kadam]

This driver adds support for loading Intel Integrated
Sensor Hub (ISH) firmware from host file system to ISH
SRAM and start execution.

At power-on, the ISH subsystem shall boot to an interim
Shim loader-firmware, which shall expose an ISHTP loader
device.

The driver implements an ISHTP client that communicates
with the Shim ISHTP loader device over the intel-ish-hid
stack, to download the main ISH firmware.

Signed-off-by: Rushikesh S Kadam <rushikesh.s.kadam@xxxxxxxxx>
---
The patches are baselined to hid git tree, branch for-5.2/ish
https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git/log/?h=for-5.2/ish

v4
 - Changed process_recv() to wake the caller in case of
   error as well. Earlier caller would wait until timeout on
   an error.
 - Change sequence of few checks in process_recv().

v3
 - Moved a couple of sanity checks from loader_cl_send() to
   process_recv().
 - Several minor changes to address review comments.

v2
 - Change loader_cl_send() so that the calling function
   shall allocate and pass the buffer to be used for
   receiving firwmare response data. Corresponding changes
   in calling function and process_recv().
 - Introduced struct response_info to encapsulate and pass
   data between from the process_recv() callback to
   calling function loader_cl_send().
 - Keep count of host firmware load retries, and fail after
   3 unsuccessful attempts.
 - Dropped report_bad_packets() function previously used for
   keeping count of bad packets.
 - Inlined loader_ish_hw_reset()'s functionality

v1
 - Initial version.

 drivers/hid/Makefile                        |    1 +
 drivers/hid/intel-ish-hid/Kconfig           |   15 +
 drivers/hid/intel-ish-hid/Makefile          |    3 +
 drivers/hid/intel-ish-hid/ishtp-fw-loader.c | 1085 +++++++++++++++++++++++++++
 4 files changed, 1104 insertions(+)
 create mode 100644 drivers/hid/intel-ish-hid/ishtp-fw-loader.c

diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 170163b..d8d393e 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -134,3 +134,4 @@ obj-$(CONFIG_USB_KBD)		+= usbhid/
 obj-$(CONFIG_I2C_HID)		+= i2c-hid/
 
 obj-$(CONFIG_INTEL_ISH_HID)	+= intel-ish-hid/
+obj-$(INTEL_ISH_FIRMWARE_DOWNLOADER)	+= intel-ish-hid/
diff --git a/drivers/hid/intel-ish-hid/Kconfig b/drivers/hid/intel-ish-hid/Kconfig
index 519e4c8..786adbc 100644
--- a/drivers/hid/intel-ish-hid/Kconfig
+++ b/drivers/hid/intel-ish-hid/Kconfig
@@ -14,4 +14,19 @@ config INTEL_ISH_HID
 	  Broxton and Kaby Lake.
 
 	  Say Y here if you want to support Intel ISH. If unsure, say N.
+
+config INTEL_ISH_FIRMWARE_DOWNLOADER
+	tristate "Host Firmware Load feature for Intel ISH"
+	depends on INTEL_ISH_HID
+	depends on X86
+	help
+	  The Integrated Sensor Hub (ISH) enables the kernel to offload
+	  sensor polling and algorithm processing to a dedicated low power
+	  processor in the chipset.
+
+	  The Host Firmware Load feature adds support to load the ISH
+	  firmware from host file system at boot.
+
+	  Say M here if you want to support Host Firmware Loading feature
+	  for Intel ISH. If unsure, say N.
 endmenu
diff --git a/drivers/hid/intel-ish-hid/Makefile b/drivers/hid/intel-ish-hid/Makefile
index 825b70a..2de97e4 100644
--- a/drivers/hid/intel-ish-hid/Makefile
+++ b/drivers/hid/intel-ish-hid/Makefile
@@ -20,4 +20,7 @@ obj-$(CONFIG_INTEL_ISH_HID) += intel-ishtp-hid.o
 intel-ishtp-hid-objs := ishtp-hid.o
 intel-ishtp-hid-objs += ishtp-hid-client.o
 
+obj-$(CONFIG_INTEL_ISH_FIRMWARE_DOWNLOADER) += intel-ishtp-loader.o
+intel-ishtp-loader-objs += ishtp-fw-loader.o
+
 ccflags-y += -Idrivers/hid/intel-ish-hid/ishtp
diff --git a/drivers/hid/intel-ish-hid/ishtp-fw-loader.c b/drivers/hid/intel-ish-hid/ishtp-fw-loader.c
new file mode 100644
index 0000000..e770e22
--- /dev/null
+++ b/drivers/hid/intel-ish-hid/ishtp-fw-loader.c
@@ -0,0 +1,1085 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ISH-TP client driver for ISH firmware loading
+ *
+ * Copyright (c) 2019, Intel Corporation.
+ */
+
+#include <linux/firmware.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/intel-ish-client-if.h>
+#include <linux/property.h>
+#include <asm/cacheflush.h>
+
+/* Number of times we attempt to load the firmware before giving up */
+#define MAX_LOAD_ATTEMPTS			3
+
+/* ISH TX/RX ring buffer pool size */
+#define LOADER_CL_RX_RING_SIZE			1
+#define LOADER_CL_TX_RING_SIZE			1
+
+/*
+ * ISH Shim firmware loader reserves 4 Kb buffer in SRAM. The buffer is
+ * used to temporarily hold the data transferred from host to Shim
+ * firmware loader. Reason for the odd size of 3968 bytes? Each IPC
+ * transfer is 128 bytes (= 4 bytes header + 124 bytes payload). So the
+ * 4 Kb buffer can hold maximum of 32 IPC transfers, which means we can
+ * have a max payload of 3968 bytes (= 32 x 124 payload).
+ */
+#define LOADER_SHIM_IPC_BUF_SIZE		3968
+
+/**
+ * enum ish_loader_commands -	ISH loader host commands.
+ * LOADER_CMD_XFER_QUERY	Query the Shim firmware loader for
+ *				capabilities
+ * LOADER_CMD_XFER_FRAGMENT	Transfer one firmware image fragment at a
+ *				time. The command may be executed
+ *				multiple times until the entire firmware
+ *				image is downloaded to SRAM.
+ * LOADER_CMD_START		Start executing the main firmware.
+ */
+enum ish_loader_commands {
+	LOADER_CMD_XFER_QUERY = 0,
+	LOADER_CMD_XFER_FRAGMENT,
+	LOADER_CMD_START,
+};
+
+/* Command bit mask */
+#define	CMD_MASK				GENMASK(6, 0)
+#define	IS_RESPONSE				BIT(7)
+
+/*
+ * ISH firmware max delay for one transmit failure is 1 Hz,
+ * and firmware will retry 2 times, so 3 Hz is used for timeout.
+ */
+#define ISHTP_SEND_TIMEOUT			(3 * HZ)
+
+/*
+ * Loader transfer modes:
+ *
+ * LOADER_XFER_MODE_ISHTP mode uses the existing ISH-TP mechanism to
+ * transfer data. This may use IPC or DMA if supported in firmware.
+ * The buffer size is limited to 4 Kb by the IPC/ISH-TP protocol for
+ * both IPC & DMA (legacy).
+ *
+ * LOADER_XFER_MODE_DIRECT_DMA - firmware loading is a bit different
+ * from the sensor data streaming. Here we download a large (300+ Kb)
+ * image directly to ISH SRAM memory. There is limited benefit of
+ * DMA'ing 300 Kb image in 4 Kb chucks limit. Hence, we introduce
+ * this "direct dma" mode, where we do not use ISH-TP for DMA, but
+ * instead manage the DMA directly in kernel driver and Shim firmware
+ * loader (allocate buffer, break in chucks and transfer). This allows
+ * to overcome 4 Kb limit, and optimize the data flow path in firmware.
+ */
+#define LOADER_XFER_MODE_DIRECT_DMA		BIT(0)
+#define LOADER_XFER_MODE_ISHTP			BIT(1)
+
+/* ISH Transport Loader client unique GUID */
+static const guid_t loader_ishtp_guid =
+	GUID_INIT(0xc804d06a, 0x55bd, 0x4ea7,
+		  0xad, 0xed, 0x1e, 0x31, 0x22, 0x8c, 0x76, 0xdc);
+
+#define FILENAME_SIZE				256
+
+/*
+ * The firmware loading latency will be minimum if we can DMA the
+ * entire ISH firmware image in one go. This requires that we allocate
+ * a large DMA buffer in kernel, which could be problematic on some
+ * platforms. So here we limit the DMA buffer size via a module_param.
+ * We default to 4 pages, but a customer can set it to higher limit if
+ * deemed appropriate for his platform.
+ */
+static int dma_buf_size_limit = 4 * PAGE_SIZE;
+
+/**
+ * struct loader_msg_hdr - Header for ISH Loader commands.
+ * @command:		LOADER_CMD* commands. Bit 7 is the response.
+ * @status:		Command response status. Non 0, is error
+ *			condition.
+ *
+ * This structure is used as header for every command/data sent/received
+ * between Host driver and ISH Shim firmware loader.
+ */
+struct loader_msg_hdr {
+	u8 command;
+	u8 reserved[2];
+	u8 status;
+} __packed;
+
+struct loader_xfer_query {
+	struct loader_msg_hdr hdr;
+	u32 image_size;
+} __packed;
+
+struct ish_fw_version {
+	u16 major;
+	u16 minor;
+	u16 hotfix;
+	u16 build;
+} __packed;
+
+union loader_version {
+	u32 value;
+	struct {
+		u8 major;
+		u8 minor;
+		u8 hotfix;
+		u8 build;
+	};
+} __packed;
+
+struct loader_capability {
+	u32 max_fw_image_size;
+	u32 xfer_mode;
+	u32 max_dma_buf_size; /* only for dma mode, multiples of cacheline */
+} __packed;
+
+struct shim_fw_info {
+	struct ish_fw_version ish_fw_version;
+	u32 protocol_version;
+	union loader_version ldr_version;
+	struct loader_capability ldr_capability;
+} __packed;
+
+struct loader_xfer_query_response {
+	struct loader_msg_hdr hdr;
+	struct shim_fw_info fw_info;
+} __packed;
+
+struct loader_xfer_fragment {
+	struct loader_msg_hdr hdr;
+	u32 xfer_mode;
+	u32 offset;
+	u32 size;
+	u32 is_last;
+} __packed;
+
+struct loader_xfer_ipc_fragment {
+	struct loader_xfer_fragment fragment;
+	u8 data[] ____cacheline_aligned; /* variable length payload here */
+} __packed;
+
+struct loader_xfer_dma_fragment {
+	struct loader_xfer_fragment fragment;
+	u64 ddr_phys_addr;
+} __packed;
+
+struct loader_start {
+	struct loader_msg_hdr hdr;
+} __packed;
+
+/**
+ * struct response_info - Encapsulate firmware response related
+ *			information for passing between function
+ *			loader_cl_send() and process_recv() callback.
+ * @data		Copy the data received from firmware here.
+ * @max_size		Max size allocated for the @data buffer. If the
+ *			received data exceeds this value, we log an
+ *			error.
+ * @size		Actual size of data received from firmware.
+ * @error		Returns 0 for success, negative error code for a
+ *			failure in function process_recv().
+ * @received		Set to true on receiving a valid firmware
+ *			response to host command
+ * @wait_queue		Wait queue for Host firmware loading where the
+ *			client sends message to ISH firmware and waits
+ *			for response
+ */
+struct response_info {
+	void *data;
+	size_t max_size;
+	size_t size;
+	int error;
+	bool received;
+	wait_queue_head_t wait_queue;
+};
+
+/**
+ * struct ishtp_cl_data - Encapsulate per ISH-TP Client Data.
+ * @work_ishtp_reset:	Work queue for reset handling.
+ * @work_fw_load:	Work queue for host firmware loading.
+ * @flag_retry		Flag for indicating host firmware loading should
+ *			be retried.
+ * @retry_count		Count the number of retries.
+ *
+ * This structure is used to store data per client.
+ */
+struct ishtp_cl_data {
+	struct ishtp_cl *loader_ishtp_cl;
+	struct ishtp_cl_device *cl_device;
+
+	/*
+	 * Used for passing firmware response information between
+	 * loader_cl_send() and process_recv() callback.
+	 */
+	struct response_info response;
+
+	struct work_struct work_ishtp_reset;
+	struct work_struct work_fw_load;
+
+	/*
+	 * In certain failure scenrios, it makes sense to reset the ISH
+	 * subsystem and retry Host firmware loading (e.g. bad message
+	 * packet, ENOMEM, etc.). On the other hand, failures due to
+	 * protocol mismatch, etc., are not recoverable. We do not
+	 * retry them.
+	 *
+	 * If set, the flag indicates that we should re-try the
+	 * particular failure.
+	 */
+	bool flag_retry;
+	int retry_count;
+};
+
+#define IPC_FRAGMENT_DATA_PREAMBLE				\
+	offsetof(struct loader_xfer_ipc_fragment, data)
+
+#define cl_data_to_dev(client_data) ishtp_device((client_data)->cl_device)
+
+/**
+ * get_firmware_variant() - Gets the filename of firmware image to be
+ *			loaded based on platform variant.
+ * @client_data		Client data instance.
+ * @filename		Returns firmware filename.
+ *
+ * Queries the firmware-name device property string.
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int get_firmware_variant(struct ishtp_cl_data *client_data,
+				char *filename)
+{
+	int rv;
+	const char *val;
+	struct device *devc = ishtp_get_pci_device(client_data->cl_device);
+
+	rv = device_property_read_string(devc, "firmware-name", &val);
+	if (rv < 0) {
+		dev_err(devc,
+			"Error: ISH firmware-name device property required\n");
+		return rv;
+	}
+	return snprintf(filename, FILENAME_SIZE, "intel/%s", val);
+}
+
+/**
+ * loader_cl_send()	Send message from host to firmware
+ * @client_data:	Client data instance
+ * @out_msg		Message buffer to be sent to firmware
+ * @out_size		Size of out going message
+ * @in_msg		Message buffer where the incoming data copied.
+ *			This buffer is allocated by calling
+ * @in_size		Max size of incoming message
+ *
+ * Return: Number of bytes copied in the in_msg on success, negative
+ * error code on failure.
+ */
+static int loader_cl_send(struct ishtp_cl_data *client_data,
+			  u8 *out_msg, size_t out_size,
+			  u8 *in_msg, size_t in_size)
+{
+	int rv;
+	struct loader_msg_hdr *out_hdr = (struct loader_msg_hdr *)out_msg;
+	struct ishtp_cl *loader_ishtp_cl = client_data->loader_ishtp_cl;
+
+	dev_dbg(cl_data_to_dev(client_data),
+		"%s: command=%02lx is_response=%u status=%02x\n",
+		__func__,
+		out_hdr->command & CMD_MASK,
+		out_hdr->command & IS_RESPONSE ? 1 : 0,
+		out_hdr->status);
+
+	/* Setup in coming buffer & size */
+	client_data->response.data = in_msg;
+	client_data->response.max_size = in_size;
+	client_data->response.error = 0;
+	client_data->response.received = false;
+
+	rv = ishtp_cl_send(loader_ishtp_cl, out_msg, out_size);
+	if (rv < 0) {
+		dev_err(cl_data_to_dev(client_data),
+			"ishtp_cl_send error %d\n", rv);
+		return rv;
+	}
+
+	wait_event_interruptible_timeout(client_data->response.wait_queue,
+					 client_data->response.received,
+					 ISHTP_SEND_TIMEOUT);
+	if (!client_data->response.received) {
+		dev_err(cl_data_to_dev(client_data),
+			"Timed out for response to command=%02lx",
+			out_hdr->command & CMD_MASK);
+		return -ETIMEDOUT;
+	}
+
+	if (client_data->response.error < 0)
+		return client_data->response.error;
+
+	return client_data->response.size;
+}
+
+/**
+ * process_recv() -	Receive and parse incoming packet
+ * @loader_ishtp_cl:	Client instance to get stats
+ * @rb_in_proc:		ISH received message buffer
+ *
+ * Parse the incoming packet. If it is a response packet then it will
+ * update received and wake up the caller waiting to for the response.
+ */
+static void process_recv(struct ishtp_cl *loader_ishtp_cl,
+			 struct ishtp_cl_rb *rb_in_proc)
+{
+	struct loader_msg_hdr *hdr;
+	size_t data_len = rb_in_proc->buf_idx;
+	struct ishtp_cl_data *client_data =
+		ishtp_get_client_data(loader_ishtp_cl);
+
+	/* Sanity check */
+	if (!client_data->response.data) {
+		dev_err(cl_data_to_dev(client_data),
+			"Receiving buffer is null. Should be allocated by calling function\n");
+		client_data->response.error = -EINVAL;
+		goto end;
+	}
+
+	if (client_data->response.received) {
+		dev_err(cl_data_to_dev(client_data),
+			"Previous firmware message not yet processed\n");
+		client_data->response.error = -EINVAL;
+		goto end;
+	}
+	/*
+	 * All firmware messages have a header. Check buffer size
+	 * before accessing elements inside.
+	 */
+	if (!rb_in_proc->buffer.data) {
+		dev_warn(cl_data_to_dev(client_data),
+			 "rb_in_proc->buffer.data returned null");
+		client_data->response.error = -EBADMSG;
+		goto end;
+	}
+
+	if (data_len < sizeof(struct loader_msg_hdr)) {
+		dev_err(cl_data_to_dev(client_data),
+			"data size %zu is less than header %zu\n",
+			data_len, sizeof(struct loader_msg_hdr));
+		client_data->response.error = -EMSGSIZE;
+		goto end;
+	}
+
+	hdr = (struct loader_msg_hdr *)rb_in_proc->buffer.data;
+
+	dev_dbg(cl_data_to_dev(client_data),
+		"%s: command=%02lx is_response=%u status=%02x\n",
+		__func__,
+		hdr->command & CMD_MASK,
+		hdr->command & IS_RESPONSE ? 1 : 0,
+		hdr->status);
+
+	if (((hdr->command & CMD_MASK) != LOADER_CMD_XFER_QUERY) &&
+	    ((hdr->command & CMD_MASK) != LOADER_CMD_XFER_FRAGMENT) &&
+	    ((hdr->command & CMD_MASK) != LOADER_CMD_START)) {
+		dev_err(cl_data_to_dev(client_data),
+			"Invalid command=%02lx\n",
+			hdr->command & CMD_MASK);
+		client_data->response.error = -EPROTO;
+		goto end;
+	}
+
+	if (data_len > client_data->response.max_size) {
+		dev_err(cl_data_to_dev(client_data),
+			"Received buffer size %zu is larger than allocated buffer %zu\n",
+			data_len, client_data->response.max_size);
+		client_data->response.error = -EMSGSIZE;
+		goto end;
+	}
+
+	/* We expect only "response" messages from firmware */
+	if (!(hdr->command & IS_RESPONSE)) {
+		dev_err(cl_data_to_dev(client_data),
+			"Invalid response to command\n");
+		client_data->response.error = -EIO;
+		goto end;
+	}
+
+	if (hdr->status) {
+		dev_err(cl_data_to_dev(client_data),
+			"Loader returned status %d\n",
+			hdr->status);
+		client_data->response.error = -EIO;
+		goto end;
+	}
+
+	/* Update the actual received buffer size */
+	client_data->response.size = data_len;
+
+	/*
+	 * Copy the buffer received in firmware response for the
+	 * calling thread.
+	 */
+	memcpy(client_data->response.data,
+	       rb_in_proc->buffer.data, data_len);
+
+	/* Set flag before waking up the caller */
+	client_data->response.received = true;
+
+end:
+	/* Free the buffer */
+	ishtp_cl_io_rb_recycle(rb_in_proc);
+	rb_in_proc = NULL;
+
+	/* Wake the calling thread */
+	wake_up_interruptible(&client_data->response.wait_queue);
+}
+
+/**
+ * loader_cl_event_cb() - bus driver callback for incoming message
+ * @device:		Pointer to the ishtp client device for which this
+ *			message is targeted
+ *
+ * Remove the packet from the list and process the message by calling
+ * process_recv
+ */
+static void loader_cl_event_cb(struct ishtp_cl_device *cl_device)
+{
+	struct ishtp_cl_rb *rb_in_proc;
+	struct ishtp_cl	*loader_ishtp_cl = ishtp_get_drvdata(cl_device);
+
+	while ((rb_in_proc = ishtp_cl_rx_get_rb(loader_ishtp_cl)) != NULL) {
+		/* Process the data packet from firmware */
+		process_recv(loader_ishtp_cl, rb_in_proc);
+	}
+}
+
+/**
+ * ish_query_loader_prop() -  Query ISH Shim firmware loader
+ * @client_data:	Client data instance
+ * @fw:			Poiner to firmware data struct in host memory
+ * @fw_info:		Loader firmware properties
+ *
+ * This function queries the ISH Shim firmware loader for capabilities.
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int ish_query_loader_prop(struct ishtp_cl_data *client_data,
+				 const struct firmware *fw,
+				 struct shim_fw_info *fw_info)
+{
+	int rv;
+	struct loader_xfer_query ldr_xfer_query;
+	struct loader_xfer_query_response ldr_xfer_query_resp;
+
+	memset(&ldr_xfer_query, 0, sizeof(ldr_xfer_query));
+	ldr_xfer_query.hdr.command = LOADER_CMD_XFER_QUERY;
+	ldr_xfer_query.image_size = fw->size;
+	rv = loader_cl_send(client_data,
+			    (u8 *)&ldr_xfer_query,
+			    sizeof(ldr_xfer_query),
+			    (u8 *)&ldr_xfer_query_resp,
+			    sizeof(ldr_xfer_query_resp));
+	if (rv < 0) {
+		client_data->flag_retry = true;
+		return rv;
+	}
+
+	/* On success, the return value is the received buffer size */
+	if (rv != sizeof(struct loader_xfer_query_response)) {
+		dev_err(cl_data_to_dev(client_data),
+			"data size %d is not equal to size of loader_xfer_query_response %zu\n",
+			rv, sizeof(struct loader_xfer_query_response));
+		client_data->flag_retry = true;
+		return -EMSGSIZE;
+	}
+
+	/* Save fw_info for use outside this function */
+	*fw_info = ldr_xfer_query_resp.fw_info;
+
+	/* Loader firmware properties */
+	dev_dbg(cl_data_to_dev(client_data),
+		"ish_fw_version: major=%d minor=%d hotfix=%d build=%d protocol_version=0x%x loader_version=%d\n",
+		fw_info->ish_fw_version.major,
+		fw_info->ish_fw_version.minor,
+		fw_info->ish_fw_version.hotfix,
+		fw_info->ish_fw_version.build,
+		fw_info->protocol_version,
+		fw_info->ldr_version.value);
+
+	dev_dbg(cl_data_to_dev(client_data),
+		"loader_capability: max_fw_image_size=0x%x xfer_mode=%d max_dma_buf_size=0x%x dma_buf_size_limit=0x%x\n",
+		fw_info->ldr_capability.max_fw_image_size,
+		fw_info->ldr_capability.xfer_mode,
+		fw_info->ldr_capability.max_dma_buf_size,
+		dma_buf_size_limit);
+
+	/* Sanity checks */
+	if (fw_info->ldr_capability.max_fw_image_size < fw->size) {
+		dev_err(cl_data_to_dev(client_data),
+			"ISH firmware size %zu is greater than Shim firmware loader max supported %d\n",
+			fw->size,
+			fw_info->ldr_capability.max_fw_image_size);
+		return -ENOSPC;
+	}
+
+	/* For DMA the buffer size should be multiple of cacheline size */
+	if ((fw_info->ldr_capability.xfer_mode & LOADER_XFER_MODE_DIRECT_DMA) &&
+	    (fw_info->ldr_capability.max_dma_buf_size % L1_CACHE_BYTES)) {
+		dev_err(cl_data_to_dev(client_data),
+			"Shim firmware loader buffer size %d should be multipe of cacheline\n",
+			fw_info->ldr_capability.max_dma_buf_size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * ish_fw_xfer_ishtp()	Loads ISH firmware using ishtp interface
+ * @client_data:	Client data instance
+ * @fw:			Pointer to firmware data struct in host memory
+ *
+ * This function uses ISH-TP to transfer ISH firmware from host to
+ * ISH SRAM. Lower layers may use IPC or DMA depending on firmware
+ * support.
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int ish_fw_xfer_ishtp(struct ishtp_cl_data *client_data,
+			     const struct firmware *fw)
+{
+	int rv;
+	u32 fragment_offset, fragment_size, payload_max_size;
+	struct loader_xfer_ipc_fragment *ldr_xfer_ipc_frag;
+	struct loader_msg_hdr ldr_xfer_ipc_ack;
+
+	payload_max_size =
+		LOADER_SHIM_IPC_BUF_SIZE - IPC_FRAGMENT_DATA_PREAMBLE;
+
+	ldr_xfer_ipc_frag = kzalloc(LOADER_SHIM_IPC_BUF_SIZE, GFP_KERNEL);
+	if (!ldr_xfer_ipc_frag) {
+		client_data->flag_retry = true;
+		return -ENOMEM;
+	}
+
+	ldr_xfer_ipc_frag->fragment.hdr.command = LOADER_CMD_XFER_FRAGMENT;
+	ldr_xfer_ipc_frag->fragment.xfer_mode = LOADER_XFER_MODE_ISHTP;
+
+	/* Break the firmware image into fragments and send as ISH-TP payload */
+	fragment_offset = 0;
+	while (fragment_offset < fw->size) {
+		if (fragment_offset + payload_max_size < fw->size) {
+			fragment_size = payload_max_size;
+			ldr_xfer_ipc_frag->fragment.is_last = 0;
+		} else {
+			fragment_size = fw->size - fragment_offset;
+			ldr_xfer_ipc_frag->fragment.is_last = 1;
+		}
+
+		ldr_xfer_ipc_frag->fragment.offset = fragment_offset;
+		ldr_xfer_ipc_frag->fragment.size = fragment_size;
+		memcpy(ldr_xfer_ipc_frag->data,
+		       &fw->data[fragment_offset],
+		       fragment_size);
+
+		dev_dbg(cl_data_to_dev(client_data),
+			"xfer_mode=ipc offset=0x%08x size=0x%08x is_last=%d\n",
+			ldr_xfer_ipc_frag->fragment.offset,
+			ldr_xfer_ipc_frag->fragment.size,
+			ldr_xfer_ipc_frag->fragment.is_last);
+
+		rv = loader_cl_send(client_data,
+				    (u8 *)ldr_xfer_ipc_frag,
+				    IPC_FRAGMENT_DATA_PREAMBLE + fragment_size,
+				    (u8 *)&ldr_xfer_ipc_ack,
+				    sizeof(ldr_xfer_ipc_ack));
+		if (rv < 0) {
+			client_data->flag_retry = true;
+			goto end_err_resp_buf_release;
+		}
+
+		fragment_offset += fragment_size;
+	}
+
+	kfree(ldr_xfer_ipc_frag);
+	return 0;
+
+end_err_resp_buf_release:
+	/* Free ISH buffer if not done already, in error case */
+	kfree(ldr_xfer_ipc_frag);
+	return rv;
+}
+
+/**
+ * ish_fw_xfer_direct_dma() - Loads ISH firmware using direct dma
+ * @client_data:	Client data instance
+ * @fw:			Pointer to firmware data struct in host memory
+ * @fw_info:		Loader firmware properties
+ *
+ * Host firmware load is a unique case where we need to download
+ * a large firmware image (200+ Kb). This function implements
+ * direct DMA transfer in kernel and ISH firmware. This allows
+ * us to overcome the ISH-TP 4 Kb limit, and allows us to DMA
+ * directly to ISH UMA at location of choice.
+ * Function depends on corresponding support in ISH firmware.
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int ish_fw_xfer_direct_dma(struct ishtp_cl_data *client_data,
+				  const struct firmware *fw,
+				  const struct shim_fw_info fw_info)
+{
+	int rv;
+	void *dma_buf;
+	dma_addr_t dma_buf_phy;
+	u32 fragment_offset, fragment_size, payload_max_size;
+	struct loader_msg_hdr ldr_xfer_dma_frag_ack;
+	struct loader_xfer_dma_fragment ldr_xfer_dma_frag;
+	struct device *devc = ishtp_get_pci_device(client_data->cl_device);
+	u32 shim_fw_buf_size =
+		fw_info.ldr_capability.max_dma_buf_size;
+
+	/*
+	 * payload_max_size should be set to minimum of
+	 *  (1) Size of firmware to be loaded,
+	 *  (2) Max DMA buffer size supported by Shim firmware,
+	 *  (3) DMA buffer size limit set by boot_param dma_buf_size_limit.
+	 */
+	payload_max_size = min3(fw->size,
+				(size_t)shim_fw_buf_size,
+				(size_t)dma_buf_size_limit);
+
+	/*
+	 * Buffer size should be multiple of cacheline size
+	 * if it's not, select the previous cacheline boundary.
+	 */
+	payload_max_size &= ~(L1_CACHE_BYTES - 1);
+
+	dma_buf = kmalloc(payload_max_size, GFP_KERNEL | GFP_DMA32);
+	if (!dma_buf) {
+		client_data->flag_retry = true;
+		return -ENOMEM;
+	}
+
+	dma_buf_phy = dma_map_single(devc, dma_buf, payload_max_size,
+				     DMA_TO_DEVICE);
+	if (dma_mapping_error(devc, dma_buf_phy)) {
+		dev_err(cl_data_to_dev(client_data), "DMA map failed\n");
+		client_data->flag_retry = true;
+		rv = -ENOMEM;
+		goto end_err_dma_buf_release;
+	}
+
+	ldr_xfer_dma_frag.fragment.hdr.command = LOADER_CMD_XFER_FRAGMENT;
+	ldr_xfer_dma_frag.fragment.xfer_mode = LOADER_XFER_MODE_DIRECT_DMA;
+	ldr_xfer_dma_frag.ddr_phys_addr = (u64)dma_buf_phy;
+
+	/* Send the firmware image in chucks of payload_max_size */
+	fragment_offset = 0;
+	while (fragment_offset < fw->size) {
+		if (fragment_offset + payload_max_size < fw->size) {
+			fragment_size = payload_max_size;
+			ldr_xfer_dma_frag.fragment.is_last = 0;
+		} else {
+			fragment_size = fw->size - fragment_offset;
+			ldr_xfer_dma_frag.fragment.is_last = 1;
+		}
+
+		ldr_xfer_dma_frag.fragment.offset = fragment_offset;
+		ldr_xfer_dma_frag.fragment.size = fragment_size;
+		memcpy(dma_buf, &fw->data[fragment_offset], fragment_size);
+
+		dma_sync_single_for_device(devc, dma_buf_phy,
+					   payload_max_size,
+					   DMA_TO_DEVICE);
+
+		/*
+		 * Flush cache here because the dma_sync_single_for_device()
+		 * does not do for x86.
+		 */
+		clflush_cache_range(dma_buf, payload_max_size);
+
+		dev_dbg(cl_data_to_dev(client_data),
+			"xfer_mode=dma offset=0x%08x size=0x%x is_last=%d ddr_phys_addr=0x%016llx\n",
+			ldr_xfer_dma_frag.fragment.offset,
+			ldr_xfer_dma_frag.fragment.size,
+			ldr_xfer_dma_frag.fragment.is_last,
+			ldr_xfer_dma_frag.ddr_phys_addr);
+
+		rv = loader_cl_send(client_data,
+				    (u8 *)&ldr_xfer_dma_frag,
+				    sizeof(ldr_xfer_dma_frag),
+				    (u8 *)&ldr_xfer_dma_frag_ack,
+				    sizeof(ldr_xfer_dma_frag_ack));
+		if (rv < 0) {
+			client_data->flag_retry = true;
+			goto end_err_resp_buf_release;
+		}
+
+		fragment_offset += fragment_size;
+	}
+
+	dma_unmap_single(devc, dma_buf_phy, payload_max_size, DMA_TO_DEVICE);
+	kfree(dma_buf);
+	return 0;
+
+end_err_resp_buf_release:
+	/* Free ISH buffer if not done already, in error case */
+	dma_unmap_single(devc, dma_buf_phy, payload_max_size, DMA_TO_DEVICE);
+end_err_dma_buf_release:
+	kfree(dma_buf);
+	return rv;
+}
+
+/**
+ * ish_fw_start()	Start executing ISH main firmware
+ * @client_data:	client data instance
+ *
+ * This function sends message to Shim firmware loader to start
+ * the execution of ISH main firmware.
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int ish_fw_start(struct ishtp_cl_data *client_data)
+{
+	struct loader_start ldr_start;
+	struct loader_msg_hdr ldr_start_ack;
+
+	memset(&ldr_start, 0, sizeof(ldr_start));
+	ldr_start.hdr.command = LOADER_CMD_START;
+	return loader_cl_send(client_data,
+			    (u8 *)&ldr_start,
+			    sizeof(ldr_start),
+			    (u8 *)&ldr_start_ack,
+			    sizeof(ldr_start_ack));
+}
+
+/**
+ * load_fw_from_host()	Loads ISH firmware from host
+ * @client_data:	Client data instance
+ *
+ * This function loads the ISH firmware to ISH SRAM and starts execution
+ *
+ * Return: 0 for success, negative error code for failure.
+ */
+static int load_fw_from_host(struct ishtp_cl_data *client_data)
+{
+	int rv;
+	u32 xfer_mode;
+	char *filename;
+	const struct firmware *fw;
+	struct shim_fw_info fw_info;
+	struct ishtp_cl *loader_ishtp_cl = client_data->loader_ishtp_cl;
+
+	client_data->flag_retry = false;
+
+	filename = kzalloc(FILENAME_SIZE, GFP_KERNEL);
+	if (!filename) {
+		client_data->flag_retry = true;
+		rv = -ENOMEM;
+		goto end_error;
+	}
+
+	/* Get filename of the ISH firmware to be loaded */
+	rv = get_firmware_variant(client_data, filename);
+	if (rv < 0)
+		goto end_err_filename_buf_release;
+
+	rv = request_firmware(&fw, filename, cl_data_to_dev(client_data));
+	if (rv < 0)
+		goto end_err_filename_buf_release;
+
+	/* Step 1: Query Shim firmware loader properties */
+
+	rv = ish_query_loader_prop(client_data, fw, &fw_info);
+	if (rv < 0)
+		goto end_err_fw_release;
+
+	/* Step 2: Send the main firmware image to be loaded, to ISH SRAM */
+
+	xfer_mode = fw_info.ldr_capability.xfer_mode;
+	if (xfer_mode & LOADER_XFER_MODE_DIRECT_DMA) {
+		rv = ish_fw_xfer_direct_dma(client_data, fw, fw_info);
+	} else if (xfer_mode & LOADER_XFER_MODE_ISHTP) {
+		rv = ish_fw_xfer_ishtp(client_data, fw);
+	} else {
+		dev_err(cl_data_to_dev(client_data),
+			"No transfer mode selected in firmware\n");
+		rv = -EINVAL;
+	}
+	if (rv < 0)
+		goto end_err_fw_release;
+
+	/* Step 3: Start ISH main firmware exeuction */
+
+	rv = ish_fw_start(client_data);
+	if (rv < 0)
+		goto end_err_fw_release;
+
+	release_firmware(fw);
+	kfree(filename);
+	dev_info(cl_data_to_dev(client_data), "ISH firmware %s loaded\n",
+		 filename);
+	return 0;
+
+end_err_fw_release:
+	release_firmware(fw);
+end_err_filename_buf_release:
+	kfree(filename);
+end_error:
+	/* Keep a count of retries, and give up after 3 attempts */
+	if (client_data->flag_retry &&
+	    client_data->retry_count++ < MAX_LOAD_ATTEMPTS) {
+		dev_warn(cl_data_to_dev(client_data),
+			 "ISH host firmware load failed %d. Resetting ISH, and trying again..\n",
+			 rv);
+		ish_hw_reset(ishtp_get_ishtp_device(loader_ishtp_cl));
+	} else {
+		dev_err(cl_data_to_dev(client_data),
+			"ISH host firmware load failed %d\n", rv);
+	}
+	return rv;
+}
+
+static void load_fw_from_host_handler(struct work_struct *work)
+{
+	struct ishtp_cl_data *client_data;
+
+	client_data = container_of(work, struct ishtp_cl_data,
+				   work_fw_load);
+	load_fw_from_host(client_data);
+}
+
+/**
+ * loader_init() -	Init function for ISH-TP client
+ * @loader_ishtp_cl:	ISH-TP client instance
+ * @reset:		true if called for init after reset
+ *
+ * Return: 0 for success, negative error code for failure
+ */
+static int loader_init(struct ishtp_cl *loader_ishtp_cl, int reset)
+{
+	int rv;
+	struct ishtp_fw_client *fw_client;
+	struct ishtp_cl_data *client_data =
+		ishtp_get_client_data(loader_ishtp_cl);
+
+	dev_dbg(cl_data_to_dev(client_data), "reset flag: %d\n", reset);
+
+	rv = ishtp_cl_link(loader_ishtp_cl);
+	if (rv < 0) {
+		dev_err(cl_data_to_dev(client_data), "ishtp_cl_link failed\n");
+		return rv;
+	}
+
+	/* Connect to firmware client */
+	ishtp_set_tx_ring_size(loader_ishtp_cl, LOADER_CL_TX_RING_SIZE);
+	ishtp_set_rx_ring_size(loader_ishtp_cl, LOADER_CL_RX_RING_SIZE);
+
+	fw_client =
+		ishtp_fw_cl_get_client(ishtp_get_ishtp_device(loader_ishtp_cl),
+				       &loader_ishtp_guid);
+	if (!fw_client) {
+		dev_err(cl_data_to_dev(client_data),
+			"ISH client uuid not found\n");
+		rv = -ENOENT;
+		goto err_cl_unlink;
+	}
+
+	ishtp_cl_set_fw_client_id(loader_ishtp_cl,
+				  ishtp_get_fw_client_id(fw_client));
+	ishtp_set_connection_state(loader_ishtp_cl, ISHTP_CL_CONNECTING);
+
+	rv = ishtp_cl_connect(loader_ishtp_cl);
+	if (rv < 0) {
+		dev_err(cl_data_to_dev(client_data), "Client connect fail\n");
+		goto err_cl_unlink;
+	}
+
+	dev_dbg(cl_data_to_dev(client_data), "Client connected\n");
+
+	ishtp_register_event_cb(client_data->cl_device, loader_cl_event_cb);
+
+	return 0;
+
+err_cl_unlink:
+	ishtp_cl_unlink(loader_ishtp_cl);
+	return rv;
+}
+
+static void loader_deinit(struct ishtp_cl *loader_ishtp_cl)
+{
+	ishtp_set_connection_state(loader_ishtp_cl, ISHTP_CL_DISCONNECTING);
+	ishtp_cl_disconnect(loader_ishtp_cl);
+	ishtp_cl_unlink(loader_ishtp_cl);
+	ishtp_cl_flush_queues(loader_ishtp_cl);
+
+	/* Disband and free all Tx and Rx client-level rings */
+	ishtp_cl_free(loader_ishtp_cl);
+}
+
+static void reset_handler(struct work_struct *work)
+{
+	int rv;
+	struct ishtp_cl_data *client_data;
+	struct ishtp_cl *loader_ishtp_cl;
+	struct ishtp_cl_device *cl_device;
+
+	client_data = container_of(work, struct ishtp_cl_data,
+				   work_ishtp_reset);
+
+	loader_ishtp_cl = client_data->loader_ishtp_cl;
+	cl_device = client_data->cl_device;
+
+	/* Unlink, flush queues & start again */
+	ishtp_cl_unlink(loader_ishtp_cl);
+	ishtp_cl_flush_queues(loader_ishtp_cl);
+	ishtp_cl_free(loader_ishtp_cl);
+
+	loader_ishtp_cl = ishtp_cl_allocate(cl_device);
+	if (!loader_ishtp_cl)
+		return;
+
+	ishtp_set_drvdata(cl_device, loader_ishtp_cl);
+	ishtp_set_client_data(loader_ishtp_cl, client_data);
+	client_data->loader_ishtp_cl = loader_ishtp_cl;
+	client_data->cl_device = cl_device;
+
+	rv = loader_init(loader_ishtp_cl, 1);
+	if (rv < 0) {
+		dev_err(ishtp_device(cl_device), "Reset Failed\n");
+		return;
+	}
+
+	/* ISH firmware loading from host */
+	load_fw_from_host(client_data);
+}
+
+/**
+ * loader_ishtp_cl_probe() - ISH-TP client driver probe
+ * @cl_device:		ISH-TP client device instance
+ *
+ * This function gets called on device create on ISH-TP bus
+ *
+ * Return: 0 for success, negative error code for failure
+ */
+static int loader_ishtp_cl_probe(struct ishtp_cl_device *cl_device)
+{
+	struct ishtp_cl *loader_ishtp_cl;
+	struct ishtp_cl_data *client_data;
+	int rv;
+
+	client_data = devm_kzalloc(ishtp_device(cl_device),
+				   sizeof(*client_data),
+				   GFP_KERNEL);
+	if (!client_data)
+		return -ENOMEM;
+
+	loader_ishtp_cl = ishtp_cl_allocate(cl_device);
+	if (!loader_ishtp_cl)
+		return -ENOMEM;
+
+	ishtp_set_drvdata(cl_device, loader_ishtp_cl);
+	ishtp_set_client_data(loader_ishtp_cl, client_data);
+	client_data->loader_ishtp_cl = loader_ishtp_cl;
+	client_data->cl_device = cl_device;
+
+	init_waitqueue_head(&client_data->response.wait_queue);
+
+	INIT_WORK(&client_data->work_ishtp_reset,
+		  reset_handler);
+	INIT_WORK(&client_data->work_fw_load,
+		  load_fw_from_host_handler);
+
+	rv = loader_init(loader_ishtp_cl, 0);
+	if (rv < 0) {
+		ishtp_cl_free(loader_ishtp_cl);
+		return rv;
+	}
+	ishtp_get_device(cl_device);
+
+	client_data->retry_count = 0;
+
+	/* ISH firmware loading from host */
+	schedule_work(&client_data->work_fw_load);
+
+	return 0;
+}
+
+/**
+ * loader_ishtp_cl_remove() - ISH-TP client driver remove
+ * @cl_device:		ISH-TP client device instance
+ *
+ * This function gets called on device remove on ISH-TP bus
+ *
+ * Return: 0
+ */
+static int loader_ishtp_cl_remove(struct ishtp_cl_device *cl_device)
+{
+	struct ishtp_cl_data *client_data;
+	struct ishtp_cl	*loader_ishtp_cl = ishtp_get_drvdata(cl_device);
+
+	client_data = ishtp_get_client_data(loader_ishtp_cl);
+
+	/*
+	 * The sequence of the following two cancel_work_sync() is
+	 * important. The work_fw_load can in turn schedue
+	 * work_ishtp_reset, so first cancel work_fw_load then
+	 * cancel work_ishtp_reset.
+	 */
+	cancel_work_sync(&client_data->work_fw_load);
+	cancel_work_sync(&client_data->work_ishtp_reset);
+	loader_deinit(loader_ishtp_cl);
+	ishtp_put_device(cl_device);
+
+	return 0;
+}
+
+/**
+ * loader_ishtp_cl_reset() - ISH-TP client driver reset
+ * @cl_device:		ISH-TP client device instance
+ *
+ * This function gets called on device reset on ISH-TP bus
+ *
+ * Return: 0
+ */
+static int loader_ishtp_cl_reset(struct ishtp_cl_device *cl_device)
+{
+	struct ishtp_cl_data *client_data;
+	struct ishtp_cl	*loader_ishtp_cl = ishtp_get_drvdata(cl_device);
+
+	client_data = ishtp_get_client_data(loader_ishtp_cl);
+
+	schedule_work(&client_data->work_ishtp_reset);
+
+	return 0;
+}
+
+static struct ishtp_cl_driver	loader_ishtp_cl_driver = {
+	.name = "ish-loader",
+	.guid = &loader_ishtp_guid,
+	.probe = loader_ishtp_cl_probe,
+	.remove = loader_ishtp_cl_remove,
+	.reset = loader_ishtp_cl_reset,
+};
+
+static int __init ish_loader_init(void)
+{
+	return ishtp_cl_driver_register(&loader_ishtp_cl_driver, THIS_MODULE);
+}
+
+static void __exit ish_loader_exit(void)
+{
+	ishtp_cl_driver_unregister(&loader_ishtp_cl_driver);
+}
+
+late_initcall(ish_loader_init);
+module_exit(ish_loader_exit);
+
+module_param(dma_buf_size_limit, int, 0644);
+MODULE_PARM_DESC(dma_buf_size_limit, "Limit the DMA buf size to this value in bytes");
+
+MODULE_DESCRIPTION("ISH ISH-TP Host firmware Loader Client Driver");
+MODULE_AUTHOR("Rushikesh S Kadam <rushikesh.s.kadam@xxxxxxxxx>");
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("ishtp:*");
-- 
1.9.1