greybus: spi: add bridged-PHY spi protocol driver

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/Makefile

@@ -15,6 +15,7 @@ gb-phy-y :=	gpb.o		\
 		pwm.o	\
 		gpio.o	\
 		i2c.o	\
+		spi.o	\
 		usb.o
 
 # Prefix all modules with gb-

drivers/staging/greybus/gpb.c

@@ -45,8 +45,14 @@ static int __init gpbridge_init(void)
 		pr_err("error initializing usb protocol\n");
 		goto error_i2c;
 	}
+	if (gb_spi_protocol_init()) {
+		pr_err("error initializing usb protocol\n");
+		goto error_spi;
+	}
 	return 0;
 
+error_spi:
+	gb_i2c_protocol_exit();
 error_i2c:
 	gb_usb_protocol_exit();
 error_usb:
@@ -63,6 +69,7 @@ static int __init gpbridge_init(void)
 
 static void __exit gpbridge_exit(void)
 {
+	gb_spi_protocol_exit();
 	gb_i2c_protocol_exit();
 	gb_usb_protocol_exit();
 	gb_sdio_protocol_exit();

drivers/staging/greybus/protocol.h

@@ -81,6 +81,9 @@ extern void gb_usb_protocol_exit(void);
 extern int gb_i2c_protocol_init(void);
 extern void gb_i2c_protocol_exit(void);
 
+extern int gb_spi_protocol_init(void);
+extern void gb_spi_protocol_exit(void);
+
 #define gb_protocol_driver(__protocol)			\
 static int __init protocol_init(void)			\
 {							\

drivers/staging/greybus/spi.c

+/*
+ * SPI bridge driver for the Greybus "generic" SPI module.
+ *
+ * Copyright 2014 Google Inc.
+ * Copyright 2014 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"
+
+struct gb_spi {
+	struct gb_connection	*connection;
+	u8			version_major;
+	u8			version_minor;
+
+	/* Modes supported by spi controller */
+	u16			mode;
+	/* constraints of the spi controller */
+	u16			flags;
+
+	/*
+	 * copied from kernel:
+	 *
+	 * A mask indicating which values of bits_per_word are supported by the
+	 * controller. Bit n indicates that a bits_per_word n+1 is suported. If
+	 * set, the SPI core will reject any transfer with an unsupported
+	 * bits_per_word. If not set, this value is simply ignored, and it's up
+	 * to the individual driver to perform any validation.
+	 */
+	u32			bits_per_word_mask;
+
+	/*
+	 * chipselects will be integral to many controllers; some others might
+	 * use board-specific GPIOs.
+	 */
+	u16			num_chipselect;
+};
+
+/* Version of the Greybus spi protocol we support */
+#define GB_SPI_VERSION_MAJOR		0x00
+#define GB_SPI_VERSION_MINOR		0x01
+
+/* Should match up with modes in linux/spi/spi.h */
+#define GB_SPI_MODE_CPHA		0x01		/* clock phase */
+#define GB_SPI_MODE_CPOL		0x02		/* clock polarity */
+#define GB_SPI_MODE_MODE_0		(0|0)		/* (original MicroWire) */
+#define GB_SPI_MODE_MODE_1		(0|GB_SPI_MODE_CPHA)
+#define GB_SPI_MODE_MODE_2		(GB_SPI_MODE_CPOL|0)
+#define GB_SPI_MODE_MODE_3		(GB_SPI_MODE_CPOL|GB_SPI_MODE_CPHA)
+#define GB_SPI_MODE_CS_HIGH		0x04		/* chipselect active high? */
+#define GB_SPI_MODE_LSB_FIRST		0x08		/* per-word bits-on-wire */
+#define GB_SPI_MODE_3WIRE		0x10		/* SI/SO signals shared */
+#define GB_SPI_MODE_LOOP		0x20		/* loopback mode */
+#define GB_SPI_MODE_NO_CS		0x40		/* 1 dev/bus, no chipselect */
+#define GB_SPI_MODE_READY		0x80		/* slave pulls low to pause */
+
+/* Should match up with flags in linux/spi/spi.h */
+#define GB_SPI_FLAG_HALF_DUPLEX		BIT(0)		/* can't do full duplex */
+#define GB_SPI_FLAG_NO_RX		BIT(1)		/* can't do buffer read */
+#define GB_SPI_FLAG_NO_TX		BIT(2)		/* can't do buffer write */
+
+/* Greybus spi request types */
+#define GB_SPI_TYPE_INVALID		0x00
+#define GB_SPI_TYPE_PROTOCOL_VERSION	0x01
+#define GB_SPI_TYPE_MODE		0x02
+#define GB_SPI_TYPE_FLAGS		0x03
+#define GB_SPI_TYPE_BITS_PER_WORD_MASK	0x04
+#define GB_SPI_TYPE_NUM_CHIPSELECT	0x05
+#define GB_SPI_TYPE_TRANSFER		0x06
+#define GB_SPI_TYPE_RESPONSE		0x80	/* OR'd with rest */
+
+/* mode request has no payload */
+struct gb_spi_mode_response {
+	__le16	mode;
+};
+
+/* flags request has no payload */
+struct gb_spi_flags_response {
+	__le16	flags;
+};
+
+/* bits-per-word request has no payload */
+struct gb_spi_bpw_response {
+	__le32	bits_per_word_mask;
+};
+
+/* num-chipselects request has no payload */
+struct gb_spi_chipselect_response {
+	__le16	num_chipselect;
+};
+
+/**
+ * struct gb_spi_transfer - a read/write buffer pair
+ * @speed_hz: Select a speed other than the device default for this transfer. If
+ *	0 the default (from @spi_device) is used.
+ * @len: size of rx and tx buffers (in bytes)
+ * @delay_usecs: microseconds to delay after this transfer before (optionally)
+ * 	changing the chipselect status, then starting the next transfer or
+ * 	completing this spi_message.
+ * @cs_change: affects chipselect after this transfer completes
+ * @bits_per_word: select a bits_per_word other than the device default for this
+ *	transfer. If 0 the default (from @spi_device) is used.
+ */
+struct gb_spi_transfer {
+	__le32		speed_hz;
+	__le32		len;
+	__le16		delay_usecs;
+	__u8		cs_change;
+	__u8		bits_per_word;
+};
+
+struct gb_spi_transfer_request {
+	__u8			chip_select;	/* of the spi device */
+	__u8			mode;		/* of the spi device */
+	__le16			count;
+	struct gb_spi_transfer	transfers[0];	/* trnasfer_count of these */
+};
+
+struct gb_spi_transfer_response {
+	__u8			data[0];	/* inbound data */
+};
+
+/* Routines to transfer data */
+static struct gb_operation *
+gb_spi_operation_create(struct gb_connection *connection,
+			struct spi_message *msg, u32 *total_len)
+{
+	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, request_size;
+	void *tx_data;
+
+	/* Find number of transfers queued and tx/rx length in the message */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (!xfer->tx_buf && !xfer->rx_buf) {
+			gb_connection_err(connection,
+					  "Bufferless transfer, length %u\n",
+					  xfer->len);
+			return NULL;
+		}
+
+		if (xfer->tx_buf)
+			tx_size += xfer->len;
+		if (xfer->rx_buf)
+			rx_size += xfer->len;
+
+		*total_len += xfer->len;
+		count++;
+	}
+
+	/* Too many transfers ? */
+	if (count > (u32)U16_MAX) {
+		gb_connection_err(connection, "transfer count (%u) too big",
+				  count);
+		return NULL;
+	}
+
+	/*
+	 * 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);
+	if (!operation)
+		return NULL;
+
+	request = operation->request->payload;
+	request->count = 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 */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		gb_xfer->speed_hz = cpu_to_le16(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;
+		gb_xfer++;
+
+		/* Copy tx data */
+		if (xfer->tx_buf) {
+			memcpy(tx_data, xfer->tx_buf, xfer->len);
+			tx_data += xfer->len;
+		}
+	}
+
+	return operation;
+}
+
+static void gb_spi_decode_response(struct spi_message *msg,
+				   struct gb_spi_transfer_response *response)
+{
+	struct spi_transfer *xfer;
+	void *rx_data = response->data;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/* Copy rx data */
+		if (xfer->rx_buf) {
+			memcpy(xfer->rx_buf, rx_data, xfer->len);
+			rx_data += xfer->len;
+		}
+	}
+}
+
+static int gb_spi_transfer_one_message(struct spi_master *master,
+				       struct spi_message *msg)
+{
+	struct gb_spi *spi = spi_master_get_devdata(master);
+	struct gb_connection *connection = spi->connection;
+	struct gb_spi_transfer_response *response;
+	struct gb_operation *operation;
+	u32 len = 0;
+	int ret;
+
+	operation = gb_spi_operation_create(connection, msg, &len);
+	if (!operation)
+		return -ENOMEM;
+
+	ret = gb_operation_request_send_sync(operation);
+	if (!ret) {
+		response = operation->response->payload;
+		if (response)
+			gb_spi_decode_response(msg, response);
+	} else {
+		pr_err("transfer operation failed (%d)\n", ret);
+	}
+	gb_operation_destroy(operation);
+
+	msg->actual_length = len;
+	msg->status = 0;
+	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 infomation */
+
+/* Define get_version() routine */
+define_get_version(gb_spi, SPI);
+
+/*
+ * 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_mode_operation(struct gb_spi *spi)
+{
+	struct gb_spi_mode_response response;
+	u16 mode;
+	int ret;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_MODE,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		return ret;
+
+	mode = le16_to_cpu(response.mode);
+	spi->mode = gb_spi_mode_map(mode);
+
+	return 0;
+}
+
+static int gb_spi_flags_operation(struct gb_spi *spi)
+{
+	struct gb_spi_flags_response response;
+	u16 flags;
+	int ret;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_FLAGS,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		return ret;
+
+	flags = le16_to_cpu(response.flags);
+	spi->flags = gb_spi_flags_map(flags);
+
+	return 0;
+}
+
+static int gb_spi_bpw_operation(struct gb_spi *spi)
+{
+	struct gb_spi_bpw_response response;
+	int ret;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_BITS_PER_WORD_MASK,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		return ret;
+
+	spi->bits_per_word_mask = le32_to_cpu(response.bits_per_word_mask);
+
+	return 0;
+}
+
+static int gb_spi_chipselect_operation(struct gb_spi *spi)
+{
+	struct gb_spi_chipselect_response response;
+	int ret;
+
+	ret = gb_operation_sync(spi->connection, GB_SPI_TYPE_NUM_CHIPSELECT,
+				NULL, 0, &response, sizeof(response));
+	if (ret)
+		return ret;
+
+	spi->num_chipselect = le32_to_cpu(response.num_chipselect);
+
+	return 0;
+}
+
+/*
+ * Initialize the spi device. This includes verifying we can support it (based
+ * on the protocol version it advertises). If that's OK, we get and cached its
+ * mode bits & flags.
+ */
+static int gb_spi_init(struct gb_spi *spi)
+{
+	int ret;
+
+	/* First thing we need to do is check the version */
+	ret = get_version(spi);
+	if (ret)
+		return ret;
+
+	/* mode never changes, just get it once */
+	ret = gb_spi_mode_operation(spi);
+	if (ret)
+		return ret;
+
+	/* flags never changes, just get it once */
+	ret = gb_spi_flags_operation(spi);
+	if (ret)
+		return ret;
+
+	/* total number of chipselects never changes, just get it once */
+	ret = gb_spi_chipselect_operation(spi);
+	if (ret)
+		return ret;
+
+	/* bits-per-word-mask never changes, just get it once */
+	return gb_spi_bpw_operation(spi);
+}
+
+static int gb_spi_connection_init(struct gb_connection *connection)
+{
+	struct gb_spi *spi;
+	struct spi_master *master;
+	int ret;
+
+	/* Allocate master with space for data */
+	master = spi_alloc_master(&connection->dev, sizeof(*spi));
+	if (!master) {
+		gb_connection_err(connection, "cannot alloc SPI master\n");
+		return -ENOMEM;
+	}
+
+	spi = spi_master_get_devdata(master);
+	spi->connection = connection;
+	connection->private = master;
+
+	ret = gb_spi_init(spi);
+	if (ret)
+		goto out_err;
+
+	master->bus_num = 0;		/* How do we get controller id here? */
+	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)
+		return 0;
+
+out_err:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static void gb_spi_connection_exit(struct gb_connection *connection)
+{
+	struct spi_master *master = connection->private;
+
+	spi_unregister_master(master);
+}
+
+static struct gb_protocol spi_protocol = {
+	.name			= "spi",
+	.id			= GREYBUS_PROTOCOL_SPI,
+	.major			= 0,
+	.minor			= 1,
+	.connection_init	= gb_spi_connection_init,
+	.connection_exit	= gb_spi_connection_exit,
+	.request_recv		= NULL,
+};
+
+int gb_spi_protocol_init(void)
+{
+	return gb_protocol_register(&spi_protocol);
+}
+
+void gb_spi_protocol_exit(void)
+{
+	gb_protocol_deregister(&spi_protocol);
+}