greybus: spi: Restructure spi.c to share it with other bundle drivers

This patch restructures spi.c as spilib core, so that the same logic can
be reused for SPI connections implemented as part of different bundle
types. This is required for Firmware Management Bundle.

Note that the 'struct gb_protocol' and its callback aren't moved to
a separate file in this commit to make its reviews easier. That will be
done by a following patch.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 583 insertions, 0 deletions

diff --git a/drivers/staging/greybus/spilib.c b/drivers/staging/greybus/spilib.c
new file mode 100644
index 000000000000..c7fe87801187
--- /dev/null
+++ b/drivers/staging/greybus/spilib.c
@@ -0,0 +1,583 @@
+/*
+ * Greybus SPI library
+ *
+ * Copyright 2014-2016 Google Inc.
+ * Copyright 2014-2016 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+
+#include "greybus.h"
+#include "gpbridge.h"
+#include "spilib.h"
+
+struct gb_spilib {
+	struct gb_connection	*connection;
+	struct device		*parent;
+	struct spi_transfer	*first_xfer;
+	struct spi_transfer	*last_xfer;
+	u32			rx_xfer_offset;
+	u32			tx_xfer_offset;
+	u32			last_xfer_size;
+	unsigned int		op_timeout;
+	u16			mode;
+	u16			flags;
+	u32			bits_per_word_mask;
+	u8			num_chipselect;
+	u32			min_speed_hz;
+	u32			max_speed_hz;
+};
+
+#define GB_SPI_STATE_MSG_DONE		((void *)0)
+#define GB_SPI_STATE_MSG_IDLE		((void *)1)
+#define GB_SPI_STATE_MSG_RUNNING	((void *)2)
+#define GB_SPI_STATE_OP_READY		((void *)3)
+#define GB_SPI_STATE_OP_DONE		((void *)4)
+#define GB_SPI_STATE_MSG_ERROR		((void *)-1)
+
+#define XFER_TIMEOUT_TOLERANCE		200
+
+static struct spi_master *get_master_from_spi(struct gb_spilib *spi)
+{
+	return gb_connection_get_data(spi->connection);
+}
+
+static int tx_header_fit_operation(u32 tx_size, u32 count, size_t data_max)
+{
+	size_t headers_size;
+
+	data_max -= sizeof(struct gb_spi_transfer_request);
+	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);
+
+	return tx_size + headers_size > data_max ? 0 : 1;
+}
+
+static size_t calc_rx_xfer_size(u32 rx_size, u32 *tx_xfer_size, u32 len,
+				size_t data_max)
+{
+	size_t rx_xfer_size;
+
+	data_max -= sizeof(struct gb_spi_transfer_response);
+
+	if (rx_size + len > data_max)
+		rx_xfer_size = data_max - rx_size;
+	else
+		rx_xfer_size = len;
+
+	/* if this is a write_read, for symmetry read the same as write */
+	if (*tx_xfer_size && rx_xfer_size > *tx_xfer_size)
+		rx_xfer_size = *tx_xfer_size;
+	if (*tx_xfer_size && rx_xfer_size < *tx_xfer_size)
+		*tx_xfer_size = rx_xfer_size;
+
+	return rx_xfer_size;
+}
+
+static size_t calc_tx_xfer_size(u32 tx_size, u32 count, size_t len,
+				size_t data_max)
+{
+	size_t headers_size;
+
+	data_max -= sizeof(struct gb_spi_transfer_request);
+	headers_size = (count + 1) * sizeof(struct gb_spi_transfer);
+
+	if (tx_size + headers_size + len > data_max)
+		return data_max - (tx_size + sizeof(struct gb_spi_transfer));
+
+	return len;
+}
+
+static void clean_xfer_state(struct gb_spilib *spi)
+{
+	spi->first_xfer = NULL;
+	spi->last_xfer = NULL;
+	spi->rx_xfer_offset = 0;
+	spi->tx_xfer_offset = 0;
+	spi->last_xfer_size = 0;
+	spi->op_timeout = 0;
+}
+
+static int setup_next_xfer(struct gb_spilib *spi, struct spi_message *msg)
+{
+	struct spi_transfer *last_xfer = spi->last_xfer;
+
+	if (msg->state != GB_SPI_STATE_OP_DONE)
+		return 0;
+
+	/*
+	 * if we transferred all content of the last transfer, reset values and
+	 * check if this was the last transfer in the message
+	 */
+	if ((spi->tx_xfer_offset + spi->last_xfer_size == last_xfer->len) ||
+	    (spi->rx_xfer_offset + spi->last_xfer_size == last_xfer->len)) {
+		spi->tx_xfer_offset = 0;
+		spi->rx_xfer_offset = 0;
+		spi->op_timeout = 0;
+		if (last_xfer == list_last_entry(&msg->transfers,
+						 struct spi_transfer,
+						 transfer_list))
+			msg->state = GB_SPI_STATE_MSG_DONE;
+		else
+			spi->first_xfer = list_next_entry(last_xfer,
+							  transfer_list);
+		return 0;
+	}
+
+	spi->first_xfer = last_xfer;
+	if (last_xfer->tx_buf)
+		spi->tx_xfer_offset += spi->last_xfer_size;
+
+	if (last_xfer->rx_buf)
+		spi->rx_xfer_offset += spi->last_xfer_size;
+
+	return 0;
+}
+
+static struct spi_transfer *get_next_xfer(struct spi_transfer *xfer,
+					  struct spi_message *msg)
+{
+	if (xfer == list_last_entry(&msg->transfers, struct spi_transfer,
+				    transfer_list))
+		return NULL;
+
+	return list_next_entry(xfer, transfer_list);
+}
+
+/* Routines to transfer data */
+static struct gb_operation *gb_spi_operation_create(struct gb_spilib *spi,
+		struct gb_connection *connection, struct spi_message *msg)
+{
+	struct gb_spi_transfer_request *request;
+	struct spi_device *dev = msg->spi;
+	struct spi_transfer *xfer;
+	struct gb_spi_transfer *gb_xfer;
+	struct gb_operation *operation;
+	u32 tx_size = 0, rx_size = 0, count = 0, xfer_len = 0, request_size;
+	u32 tx_xfer_size = 0, rx_xfer_size = 0, len;
+	u32 total_len = 0;
+	unsigned int xfer_timeout;
+	size_t data_max;
+	void *tx_data;
+
+	data_max = gb_operation_get_payload_size_max(connection);
+	xfer = spi->first_xfer;
+
+	/* Find number of transfers queued and tx/rx length in the message */
+
+	while (msg->state != GB_SPI_STATE_OP_READY) {
+		msg->state = GB_SPI_STATE_MSG_RUNNING;
+		spi->last_xfer = xfer;
+
+		if (!xfer->tx_buf && !xfer->rx_buf) {
+			dev_err(spi->parent,
+				"bufferless transfer, length %u\n", xfer->len);
+			msg->state = GB_SPI_STATE_MSG_ERROR;
+			return NULL;
+		}
+
+		tx_xfer_size = 0;
+		rx_xfer_size = 0;
+
+		if (xfer->tx_buf) {
+			len = xfer->len - spi->tx_xfer_offset;
+			if (!tx_header_fit_operation(tx_size, count, data_max))
+				break;
+			tx_xfer_size = calc_tx_xfer_size(tx_size, count,
+							 len, data_max);
+			spi->last_xfer_size = tx_xfer_size;
+		}
+
+		if (xfer->rx_buf) {
+			len = xfer->len - spi->rx_xfer_offset;
+			rx_xfer_size = calc_rx_xfer_size(rx_size, &tx_xfer_size,
+							 len, data_max);
+			spi->last_xfer_size = rx_xfer_size;
+		}
+
+		tx_size += tx_xfer_size;
+		rx_size += rx_xfer_size;
+
+		total_len += spi->last_xfer_size;
+		count++;
+
+		xfer = get_next_xfer(xfer, msg);
+		if (!xfer || total_len >= data_max)
+			msg->state = GB_SPI_STATE_OP_READY;
+	}
+
+	/*
+	 * In addition to space for all message descriptors we need
+	 * to have enough to hold all tx data.
+	 */
+	request_size = sizeof(*request);
+	request_size += count * sizeof(*gb_xfer);
+	request_size += tx_size;
+
+	/* Response consists only of incoming data */
+	operation = gb_operation_create(connection, GB_SPI_TYPE_TRANSFER,
+					request_size, rx_size, GFP_KERNEL);
+	if (!operation)
+		return NULL;
+
+	request = operation->request->payload;
+	request->count = cpu_to_le16(count);
+	request->mode = dev->mode;
+	request->chip_select = dev->chip_select;
+
+	gb_xfer = &request->transfers[0];
+	tx_data = gb_xfer + count;	/* place tx data after last gb_xfer */
+
+	/* Fill in the transfers array */
+	xfer = spi->first_xfer;
+	while (msg->state != GB_SPI_STATE_OP_DONE) {
+		if (xfer == spi->last_xfer)
+			xfer_len = spi->last_xfer_size;
+		else
+			xfer_len = xfer->len;
+
+		/* make sure we do not timeout in a slow transfer */
+		xfer_timeout = xfer_len * 8 * MSEC_PER_SEC / xfer->speed_hz;
+		xfer_timeout += GB_OPERATION_TIMEOUT_DEFAULT;
+
+		if (xfer_timeout > spi->op_timeout)
+			spi->op_timeout = xfer_timeout;
+
+		gb_xfer->speed_hz = cpu_to_le32(xfer->speed_hz);
+		gb_xfer->len = cpu_to_le32(xfer_len);
+		gb_xfer->delay_usecs = cpu_to_le16(xfer->delay_usecs);
+		gb_xfer->cs_change = xfer->cs_change;
+		gb_xfer->bits_per_word = xfer->bits_per_word;
+
+		/* Copy tx data */
+		if (xfer->tx_buf) {
+			gb_xfer->rdwr |= GB_SPI_XFER_WRITE;
+			memcpy(tx_data, xfer->tx_buf + spi->tx_xfer_offset,
+			       xfer_len);
+			tx_data += xfer_len;
+		}
+
+		if (xfer->rx_buf)
+			gb_xfer->rdwr |= GB_SPI_XFER_READ;
+
+		if (xfer == spi->last_xfer) {
+			msg->state = GB_SPI_STATE_OP_DONE;
+			continue;
+		}
+
+		gb_xfer++;
+		xfer = get_next_xfer(xfer, msg);
+	}
+
+	msg->actual_length += total_len;
+
+	return operation;
+}
+
+static void gb_spi_decode_response(struct gb_spilib *spi,
+				   struct spi_message *msg,
+				   struct gb_spi_transfer_response *response)
+{
+	struct spi_transfer *xfer = spi->first_xfer;
+	void *rx_data = response->data;
+	u32 xfer_len;
+
+	while (xfer) {
+		/* Copy rx data */
+		if (xfer->rx_buf) {
+			if (xfer == spi->first_xfer)
+				xfer_len = xfer->len - spi->rx_xfer_offset;
+			else if (xfer == spi->last_xfer)
+				xfer_len = spi->last_xfer_size;
+			else
+				xfer_len = xfer->len;
+
+			memcpy(xfer->rx_buf + spi->rx_xfer_offset, rx_data,
+			       xfer_len);
+			rx_data += xfer_len;
+		}
+
+		if (xfer == spi->last_xfer)
+			break;
+
+		xfer = list_next_entry(xfer, transfer_list);
+	}
+}
+
+static int gb_spi_transfer_one_message(struct spi_master *master,
+				       struct spi_message *msg)
+{
+	struct gb_spilib *spi = spi_master_get_devdata(master);
+	struct gb_connection *connection = spi->connection;
+	struct gb_spi_transfer_response *response;
+	struct gb_operation *operation;
+	int ret = 0;
+
+	spi->first_xfer = list_first_entry_or_null(&msg->transfers,
+						   struct spi_transfer,
+						   transfer_list);
+	if (!spi->first_xfer) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	msg->state = GB_SPI_STATE_MSG_IDLE;
+
+	while (msg->state != GB_SPI_STATE_MSG_DONE &&
+	       msg->state != GB_SPI_STATE_MSG_ERROR) {
+		operation = gb_spi_operation_create(spi, connection, msg);
+		if (!operation) {
+			msg->state = GB_SPI_STATE_MSG_ERROR;
+			ret = -EINVAL;
+			continue;
+		}
+
+		ret = gb_operation_request_send_sync_timeout(operation,
+							     spi->op_timeout);
+		if (!ret) {
+			response = operation->response->payload;
+			if (response)
+				gb_spi_decode_response(spi, msg, response);
+		} else {
+			dev_err(spi->parent,
+				"transfer operation failed: %d\n", ret);
+			msg->state = GB_SPI_STATE_MSG_ERROR;
+		}
+
+		gb_operation_put(operation);
+		setup_next_xfer(spi, msg);
+	}
+
+out:
+	msg->status = ret;
+	clean_xfer_state(spi);
+	spi_finalize_current_message(master);
+
+	return ret;
+}
+
+static int gb_spi_setup(struct spi_device *spi)
+{
+	/* Nothing to do for now */
+	return 0;
+}
+
+static void gb_spi_cleanup(struct spi_device *spi)
+{
+	/* Nothing to do for now */
+}
+
+
+/* Routines to get controller information */
+
+/*
+ * Map Greybus spi mode bits/flags/bpw into Linux ones.
+ * All bits are same for now and so these macro's return same values.
+ */
+#define gb_spi_mode_map(mode) mode
+#define gb_spi_flags_map(flags) flags
+
+static int gb_spi_get_master_config(struct gb_spilib *spi)
+{
+	struct gb_spi_master_config_response response;
+	u16 mode, flags;
+	int ret;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_MASTER_CONFIG,
+				NULL, 0, &response, sizeof(response));
+	if (ret < 0)
+		return ret;
+
+	mode = le16_to_cpu(response.mode);
+	spi->mode = gb_spi_mode_map(mode);
+
+	flags = le16_to_cpu(response.flags);
+	spi->flags = gb_spi_flags_map(flags);
+
+	spi->bits_per_word_mask = le32_to_cpu(response.bits_per_word_mask);
+	spi->num_chipselect = response.num_chipselect;
+
+	spi->min_speed_hz = le32_to_cpu(response.min_speed_hz);
+	spi->max_speed_hz = le32_to_cpu(response.max_speed_hz);
+
+	return 0;
+}
+
+static int gb_spi_setup_device(struct gb_spilib *spi, u8 cs)
+{
+	struct spi_master *master = get_master_from_spi(spi);
+	struct gb_spi_device_config_request request;
+	struct gb_spi_device_config_response response;
+	struct spi_board_info spi_board = { {0} };
+	struct spi_device *spidev;
+	int ret;
+	u8 dev_type;
+
+	request.chip_select = cs;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_DEVICE_CONFIG,
+				&request, sizeof(request),
+				&response, sizeof(response));
+	if (ret < 0)
+		return ret;
+
+	dev_type = response.device_type;
+
+	if (dev_type == GB_SPI_SPI_DEV)
+		strlcpy(spi_board.modalias, SPI_DEV_MODALIAS,
+			sizeof(spi_board.modalias));
+	else if (dev_type == GB_SPI_SPI_NOR)
+		strlcpy(spi_board.modalias, SPI_NOR_MODALIAS,
+			sizeof(spi_board.modalias));
+	else if (dev_type == GB_SPI_SPI_MODALIAS)
+		memcpy(spi_board.modalias, response.name,
+		       sizeof(spi_board.modalias));
+	else
+		return -EINVAL;
+
+	spi_board.mode		= le16_to_cpu(response.mode);
+	spi_board.bus_num	= master->bus_num;
+	spi_board.chip_select	= cs;
+	spi_board.max_speed_hz	= le32_to_cpu(response.max_speed_hz);
+
+	spidev = spi_new_device(master, &spi_board);
+	if (!spidev)
+		return -EINVAL;
+
+	return 0;
+}
+
+int gb_spilib_master_init(struct gb_connection *connection, struct device *dev)
+{
+	struct gb_spilib *spi;
+	struct spi_master *master;
+	int ret;
+	u8 i;
+
+	/* Allocate master with space for data */
+	master = spi_alloc_master(dev, sizeof(*spi));
+	if (!master) {
+		dev_err(dev, "cannot alloc SPI master\n");
+		return -ENOMEM;
+	}
+
+	spi = spi_master_get_devdata(master);
+	spi->connection = connection;
+	gb_connection_set_data(connection, master);
+	spi->parent = dev;
+
+	/* get master configuration */
+	ret = gb_spi_get_master_config(spi);
+	if (ret)
+		goto exit_spi_put;
+
+	master->bus_num = -1; /* Allow spi-core to allocate it dynamically */
+	master->num_chipselect = spi->num_chipselect;
+	master->mode_bits = spi->mode;
+	master->flags = spi->flags;
+	master->bits_per_word_mask = spi->bits_per_word_mask;
+
+	/* Attach methods */
+	master->cleanup = gb_spi_cleanup;
+	master->setup = gb_spi_setup;
+	master->transfer_one_message = gb_spi_transfer_one_message;
+
+	ret = spi_register_master(master);
+	if (ret < 0)
+		goto exit_spi_put;
+
+	/* now, fetch the devices configuration */
+	for (i = 0; i < spi->num_chipselect; i++) {
+		ret = gb_spi_setup_device(spi, i);
+		if (ret < 0) {
+			dev_err(dev, "failed to allocate spi device %d: %d\n",
+				i, ret);
+			goto exit_spi_unregister;
+		}
+	}
+
+	return 0;
+
+exit_spi_unregister:
+	spi_unregister_master(master);
+exit_spi_put:
+	spi_master_put(master);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gb_spilib_master_init);
+
+void gb_spilib_master_exit(struct gb_connection *connection)
+{
+	struct spi_master *master = gb_connection_get_data(connection);
+
+	spi_unregister_master(master);
+	spi_master_put(master);
+}
+EXPORT_SYMBOL_GPL(gb_spilib_master_exit);
+
+static int gb_spi_probe(struct gpbridge_device *gpbdev,
+			const struct gpbridge_device_id *id)
+{
+	struct gb_connection *connection;
+	int ret;
+
+	connection = gb_connection_create(gpbdev->bundle,
+					  le16_to_cpu(gpbdev->cport_desc->id),
+					  NULL);
+	if (IS_ERR(connection))
+		return PTR_ERR(connection);
+
+	ret = gb_connection_enable(connection);
+	if (ret)
+		goto exit_connection_destroy;
+
+	ret = gb_gpbridge_get_version(connection);
+	if (ret)
+		goto exit_connection_disable;
+
+	ret = gb_spilib_master_init(connection, &gpbdev->dev);
+	if (ret)
+		goto exit_connection_disable;
+
+	gb_gpbridge_set_data(gpbdev, connection);
+
+	return 0;
+
+exit_connection_disable:
+	gb_connection_disable(connection);
+exit_connection_destroy:
+	gb_connection_destroy(connection);
+
+	return ret;
+}
+
+static void gb_spi_remove(struct gpbridge_device *gpbdev)
+{
+	struct gb_connection *connection = gb_gpbridge_get_data(gpbdev);
+
+	gb_spilib_master_exit(connection);
+	gb_connection_disable(connection);
+	gb_connection_destroy(connection);
+}
+
+static const struct gpbridge_device_id gb_spi_id_table[] = {
+	{ GPBRIDGE_PROTOCOL(GREYBUS_PROTOCOL_SPI) },
+	{ },
+};
+MODULE_DEVICE_TABLE(gpbridge, gb_spi_id_table);
+
+static struct gpbridge_driver spi_driver = {
+	.name		= "spi",
+	.probe		= gb_spi_probe,
+	.remove		= gb_spi_remove,
+	.id_table	= gb_spi_id_table,
+};
+
+module_gpbridge_driver(spi_driver);
+MODULE_LICENSE("GPL v2");