Message-Id: <20190221202506.17744-3-agust@denx.de>
Date:   Thu, 21 Feb 2019 21:25:05 +0100
From:   Anatolij Gustschin <agust@...x.de>
To:     linux-usb@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, broonie@...nel.org, atull@...nel.org,
        mdf@...nel.org
Subject: [PATCH v4 2/3] spi: add FTDI MPSSE SPI controller driver

Add SPI bus controller driver for FTDI MPSSE mode. This driver
is supposed to be used together with the FT232H interface driver
for FPGA configuration in drivers/usb/misc/ft232h-intf.c which
adds an mpsse spi platform device describing USB SPI bus with
attached SPI slave devices.

Signed-off-by: Anatolij Gustschin <agust@...x.de>
---
 drivers/spi/Kconfig          |   7 +
 drivers/spi/Makefile         |   1 +
 drivers/spi/spi-ftdi-mpsse.c | 651 +++++++++++++++++++++++++++++++++++
 3 files changed, 659 insertions(+)
 create mode 100644 drivers/spi/spi-ftdi-mpsse.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index f761655e2a36..38015574e2dc 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -289,6 +289,13 @@ config SPI_NXP_FLEXSPI
 	  This controller does not support generic SPI messages and only
 	  supports the high-level SPI memory interface.
 
+config SPI_FTDI_MPSSE
+	tristate "FTDI MPSSE SPI controller"
+	depends on USB_FT232H_INTF || COMPILE_TEST
+	help
+	  FT232H supports SPI in MPSSE mode. This driver provides MPSSE
+	  SPI controller in master mode.
+
 config SPI_GPIO
 	tristate "GPIO-based bitbanging SPI Master"
 	depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index d8fc03c9faa2..2a1fd2c4d2bd 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_SPI_FSL_ESPI)		+= spi-fsl-espi.o
 obj-$(CONFIG_SPI_FSL_LPSPI)		+= spi-fsl-lpspi.o
 obj-$(CONFIG_SPI_FSL_QUADSPI)		+= spi-fsl-qspi.o
 obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
+obj-$(CONFIG_SPI_FTDI_MPSSE)		+= spi-ftdi-mpsse.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
 obj-$(CONFIG_SPI_IMX)			+= spi-imx.o
diff --git a/drivers/spi/spi-ftdi-mpsse.c b/drivers/spi/spi-ftdi-mpsse.c
new file mode 100644
index 000000000000..ae8442eb4052
--- /dev/null
+++ b/drivers/spi/spi-ftdi-mpsse.c
@@ -0,0 +1,651 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// FTDI FT232H MPSSE SPI controller driver
+//
+// Copyright (C) 2017 - 2018 DENX Software Engineering
+// Anatolij Gustschin <agust@...x.de>
+//
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/machine.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/sizes.h>
+#include <linux/usb.h>
+#include <linux/usb/ft232h-intf.h>
+
+enum gpiol {
+	MPSSE_SK	= BIT(0),
+	MPSSE_DO	= BIT(1),
+	MPSSE_DI	= BIT(2),
+	MPSSE_CS	= BIT(3),
+};
+
+struct ftdi_spi {
+	struct platform_device *pdev;
+	struct usb_interface *intf;
+	struct spi_controller *master;
+	const struct ft232h_intf_ops *iops;
+	struct gpiod_lookup_table *lookup[FTDI_MPSSE_GPIOS];
+	struct gpio_desc **cs_gpios;
+
+	u8 txrx_cmd;
+	u8 rx_cmd;
+	u8 tx_cmd;
+	u8 xfer_buf[SZ_64K];
+	u16 last_mode;
+};
+
+static void ftdi_spi_set_cs(struct spi_device *spi, bool enable)
+{
+	struct ftdi_spi *priv = spi_controller_get_devdata(spi->master);
+	u16 cs = spi->chip_select;
+
+	dev_dbg(&priv->pdev->dev, "%s: CS %u, cs mode %d, val %d\n",
+		__func__, cs, (spi->mode & SPI_CS_HIGH), enable);
+
+	gpiod_set_raw_value_cansleep(priv->cs_gpios[cs], enable);
+}
+
+static inline u8 ftdi_spi_txrx_byte_cmd(struct spi_device *spi)
+{
+	u8 mode = spi->mode & (SPI_CPOL | SPI_CPHA);
+	u8 cmd;
+
+	if (spi->mode & SPI_LSB_FIRST) {
+		switch (mode) {
+		case SPI_MODE_0:
+		case SPI_MODE_1:
+			cmd = TXF_RXR_BYTES_LSB;
+			break;
+		case SPI_MODE_2:
+		case SPI_MODE_3:
+			cmd = TXR_RXF_BYTES_LSB;
+			break;
+		}
+	} else {
+		switch (mode) {
+		case SPI_MODE_0:
+		case SPI_MODE_1:
+			cmd = TXF_RXR_BYTES_MSB;
+			break;
+		case SPI_MODE_2:
+		case SPI_MODE_3:
+			cmd = TXR_RXF_BYTES_MSB;
+			break;
+		}
+	}
+	return cmd;
+}
+
+static inline int ftdi_spi_loopback_cfg(struct ftdi_spi *priv, int on)
+{
+	int ret;
+
+	priv->xfer_buf[0] = on ? LOOPBACK_ON : LOOPBACK_OFF;
+
+	ret = priv->iops->write_data(priv->intf, priv->xfer_buf, 1);
+	if (ret < 0)
+		dev_warn(&priv->pdev->dev, "loopback %d failed\n", on);
+	return ret;
+}
+
+static int ftdi_spi_tx_rx(struct ftdi_spi *priv, struct spi_device *spi,
+			  struct spi_transfer *t)
+{
+	const struct ft232h_intf_ops *ops = priv->iops;
+	struct device *dev = &priv->pdev->dev;
+	void *rx_offs;
+	const void *tx_offs;
+	size_t remaining, stride;
+	size_t rx_stride;
+	int ret, tout = 10;
+	const u8 *tx_data = t->tx_buf;
+	u8 *rx_data = t->rx_buf;
+
+	ops->lock(priv->intf);
+
+	if (spi->mode & SPI_LOOP) {
+		ret = ftdi_spi_loopback_cfg(priv, 1);
+		if (ret < 0)
+			goto err;
+	}
+
+	remaining = t->len;
+	rx_offs = rx_data;
+	tx_offs = tx_data;
+
+	while (remaining) {
+		stride = min_t(size_t, remaining, SZ_512 - 3);
+
+		priv->xfer_buf[0] = priv->txrx_cmd;
+		priv->xfer_buf[1] = stride - 1;
+		priv->xfer_buf[2] = (stride - 1) >> 8;
+		memcpy(&priv->xfer_buf[3], tx_offs, stride);
+		print_hex_dump_debug("WR: ", DUMP_PREFIX_OFFSET, 16, 1,
+				     priv->xfer_buf, stride + 3, 1);
+
+		ret = ops->write_data(priv->intf, priv->xfer_buf, stride + 3);
+		if (ret < 0) {
+			dev_err(dev, "%s: xfer failed %d\n", __func__, ret);
+			goto fail;
+		}
+		dev_dbg(dev, "%s: WR %zu byte(s), TXRX CMD 0x%02x\n",
+			__func__, stride, priv->txrx_cmd);
+
+		rx_stride = min_t(size_t, stride, SZ_512);
+
+		ret = ops->read_data(priv->intf, priv->xfer_buf, rx_stride);
+		while (ret == 0) {
+			/* If no data yet, wait and repeat */
+			usleep_range(5000, 5100);
+			ret = ops->read_data(priv->intf, priv->xfer_buf,
+					     rx_stride);
+			dev_dbg(dev, "Waiting data ready, read: %d\n", ret);
+			if (!--tout) {
+				dev_err(dev, "Read timeout\n");
+				ret = -ETIMEDOUT;
+				goto fail;
+			}
+		}
+
+		if (ret < 0)
+			goto fail;
+
+		print_hex_dump_debug("RD: ", DUMP_PREFIX_OFFSET, 16, 1,
+				     priv->xfer_buf, rx_stride, 1);
+		memcpy(rx_offs, priv->xfer_buf, ret);
+		rx_offs += ret;
+
+		remaining -= stride;
+		tx_offs += stride;
+		dev_dbg(dev, "%s: WR remains %zu\n", __func__, remaining);
+	}
+
+	ret = 0;
+
+fail:
+	if (spi->mode & SPI_LOOP)
+		ftdi_spi_loopback_cfg(priv, 0);
+
+err:
+	ops->unlock(priv->intf);
+	return ret;
+}
+
+static int ftdi_spi_push_buf(struct ftdi_spi *priv, const void *buf, size_t len)
+{
+	size_t bytesleft = len;
+	int ret;
+
+	do {
+		ret = priv->iops->write_data(priv->intf, buf, bytesleft);
+		if (ret < 0)
+			return ret;
+
+		buf += ret;
+		bytesleft -= ret;
+	} while (bytesleft);
+
+	return len;
+}
+
+static int ftdi_spi_tx(struct ftdi_spi *priv, struct spi_transfer *xfer)
+{
+	const void *tx_offs;
+	size_t remaining, stride;
+	int ret;
+
+	priv->iops->lock(priv->intf);
+
+	tx_offs = xfer->tx_buf;
+	remaining = xfer->len;
+
+	do {
+		stride = min_t(size_t, remaining, sizeof(priv->xfer_buf) - 3);
+
+		priv->xfer_buf[0] = priv->tx_cmd;
+		priv->xfer_buf[1] = stride - 1;
+		priv->xfer_buf[2] = (stride - 1) >> 8;
+
+		memcpy(&priv->xfer_buf[3], tx_offs, stride);
+
+		ret = ftdi_spi_push_buf(priv, priv->xfer_buf, stride + 3);
+		if (ret < 0) {
+			dev_dbg(&priv->pdev->dev, "%s: tx failed %d\n",
+				__func__, ret);
+			goto err;
+		}
+		dev_dbg(&priv->pdev->dev, "%s: %zu byte(s) done\n",
+			__func__, stride);
+		remaining -= stride;
+		tx_offs += stride;
+	} while (remaining);
+
+	ret = 0;
+err:
+	priv->iops->unlock(priv->intf);
+	return ret;
+}
+
+static int ftdi_spi_rx(struct ftdi_spi *priv, struct spi_transfer *xfer)
+{
+	const struct ft232h_intf_ops *ops = priv->iops;
+	struct device *dev = &priv->pdev->dev;
+	size_t remaining, stride;
+	int ret, tout = 10;
+	void *rx_offs;
+
+	dev_dbg(dev, "%s: CMD 0x%02x, len %u\n",
+		__func__, priv->rx_cmd, xfer->len);
+
+	priv->xfer_buf[0] = priv->rx_cmd;
+	priv->xfer_buf[1] = xfer->len - 1;
+	priv->xfer_buf[2] = (xfer->len - 1) >> 8;
+
+	ops->lock(priv->intf);
+
+	ret = ops->write_data(priv->intf, priv->xfer_buf, 3);
+	if (ret < 0)
+		goto err;
+
+	remaining = xfer->len;
+	rx_offs = xfer->rx_buf;
+
+	do {
+		stride = min_t(size_t, remaining, SZ_512);
+
+		ret = ops->read_data(priv->intf, priv->xfer_buf, stride);
+		if (ret < 0)
+			goto err;
+
+		if (!ret) {
+			dev_dbg(dev, "Waiting for data (read: %02X), tout %d\n",
+				ret, tout);
+			if (--tout)
+				continue;
+
+			dev_dbg(dev, "read timeout...\n");
+			ret = -ETIMEDOUT;
+			goto err;
+		}
+
+		memcpy(rx_offs, priv->xfer_buf, ret);
+
+		dev_dbg(dev, "%s: %d byte(s)\n", __func__, ret);
+		rx_offs += ret;
+		remaining -= ret;
+	} while (remaining);
+
+	ret = 0;
+err:
+	ops->unlock(priv->intf);
+	return ret;
+}
+
+static int ftdi_spi_transfer_one(struct spi_controller *ctlr,
+				 struct spi_device *spi,
+				 struct spi_transfer *xfer)
+{
+	struct ftdi_spi *priv = spi_controller_get_devdata(ctlr);
+	struct device *dev = &priv->pdev->dev;
+	int ret = 0;
+
+	if (!xfer->len)
+		return 0;
+
+	if (priv->last_mode != spi->mode) {
+		u8 spi_mode = spi->mode & (SPI_CPOL | SPI_CPHA);
+		u8 pins = 0;
+
+		dev_dbg(dev, "%s: MODE 0x%x\n", __func__, spi->mode);
+
+		if (spi->mode & SPI_LSB_FIRST) {
+			switch (spi_mode) {
+			case SPI_MODE_0:
+			case SPI_MODE_3:
+				priv->tx_cmd = TX_BYTES_FE_LSB;
+				priv->rx_cmd = RX_BYTES_RE_LSB;
+				break;
+			case SPI_MODE_1:
+			case SPI_MODE_2:
+				priv->tx_cmd = TX_BYTES_RE_LSB;
+				priv->rx_cmd = RX_BYTES_FE_LSB;
+				break;
+			}
+		} else {
+			switch (spi_mode) {
+			case SPI_MODE_0:
+			case SPI_MODE_3:
+				priv->tx_cmd = TX_BYTES_FE_MSB;
+				priv->rx_cmd = RX_BYTES_RE_MSB;
+				break;
+			case SPI_MODE_1:
+			case SPI_MODE_2:
+				priv->tx_cmd = TX_BYTES_RE_MSB;
+				priv->rx_cmd = RX_BYTES_FE_MSB;
+				break;
+			}
+		}
+
+		priv->txrx_cmd = ftdi_spi_txrx_byte_cmd(spi);
+
+		switch (spi_mode) {
+		case SPI_MODE_2:
+		case SPI_MODE_3:
+			pins |= MPSSE_SK;
+			break;
+		}
+
+		ret = priv->iops->cfg_bus_pins(priv->intf,
+					       MPSSE_SK | MPSSE_DO, pins);
+		if (ret < 0) {
+			dev_err(dev, "IO cfg failed: %d\n", ret);
+			return ret;
+		}
+		priv->last_mode = spi->mode;
+	}
+
+	dev_dbg(dev, "%s: mode 0x%x, CMD RX/TX 0x%x/0x%x\n",
+		__func__, spi->mode, priv->rx_cmd, priv->tx_cmd);
+
+	if (xfer->tx_buf && xfer->rx_buf)
+		ret = ftdi_spi_tx_rx(priv, spi, xfer);
+	else if (xfer->tx_buf)
+		ret = ftdi_spi_tx(priv, xfer);
+	else if (xfer->rx_buf)
+		ret = ftdi_spi_rx(priv, xfer);
+
+	dev_dbg(dev, "%s: xfer ret %d\n", __func__, ret);
+
+	spi_finalize_current_transfer(ctlr);
+	return ret;
+}
+
+static int ftdi_mpsse_init(struct ftdi_spi *priv)
+{
+	struct platform_device *pdev = priv->pdev;
+	int ret;
+
+	dev_dbg(&pdev->dev, "MPSSE init\n");
+
+	/* Setup and send off the Hi-Speed specific commands for the FTx232H */
+	priv->xfer_buf[0] = DIS_DIV_5;      /* Use 60MHz master clock */
+	priv->xfer_buf[1] = DIS_ADAPTIVE;   /* Turn off adaptive clocking */
+	priv->xfer_buf[2] = DIS_3_PHASE;    /* Disable three-phase clocking */
+
+	priv->iops->lock(priv->intf);
+
+	ret = priv->iops->write_data(priv->intf, priv->xfer_buf, 3);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Clk cfg failed: %d\n", ret);
+		priv->iops->unlock(priv->intf);
+		return ret;
+	}
+
+	priv->xfer_buf[0] = TCK_DIVISOR;
+	priv->xfer_buf[1] = div_value(60000000);
+	priv->xfer_buf[2] = div_value(60000000) >> 8;
+	dev_dbg(&pdev->dev, "TCK_DIVISOR: 0x%04x 0x%04x\n",
+		priv->xfer_buf[1], priv->xfer_buf[2]);
+
+	ret = priv->iops->write_data(priv->intf, priv->xfer_buf, 3);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Clk cfg failed: %d\n", ret);
+		priv->iops->unlock(priv->intf);
+		return ret;
+	}
+
+	priv->iops->unlock(priv->intf);
+
+	ret = priv->iops->cfg_bus_pins(priv->intf, MPSSE_SK | MPSSE_DO, 0);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Can't init SPI bus pins: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ftdi_spi_init_io(struct spi_controller *master, unsigned int dev_idx)
+{
+	struct ftdi_spi *priv = spi_controller_get_devdata(master);
+	struct platform_device *pdev = priv->pdev;
+	const struct mpsse_spi_platform_data *pd;
+	const struct mpsse_spi_dev_data *data;
+	struct gpiod_lookup_table *lookup;
+	size_t lookup_size, size;
+	char *label;
+	unsigned int i;
+	u16 cs;
+
+	pd = pdev->dev.platform_data;
+
+	data = pd->spi_info[dev_idx].platform_data;
+	if (!data || data->magic != FTDI_MPSSE_IO_DESC_MAGIC)
+		return 0;
+
+	size = data->desc_len + 1;
+
+	lookup_size = sizeof(*lookup) + size * sizeof(struct gpiod_lookup);
+	lookup = devm_kzalloc(&pdev->dev, lookup_size, GFP_KERNEL);
+	if (!lookup)
+		return -ENOMEM;
+
+	cs = pd->spi_info[dev_idx].chip_select;
+
+	lookup->dev_id = devm_kasprintf(&pdev->dev, GFP_KERNEL, "spi%d.%d",
+					master->bus_num, cs);
+	if (!lookup->dev_id) {
+		devm_kfree(&pdev->dev, lookup);
+		return -ENOMEM;
+	}
+	dev_dbg(&pdev->dev, "LOOKUP ID '%s'\n", lookup->dev_id);
+
+	label = devm_kasprintf(&pdev->dev, GFP_KERNEL, "ftdi-mpsse-gpio.%d",
+			       pdev->id);
+	if (!label) {
+		devm_kfree(&pdev->dev, (void *)lookup->dev_id);
+		devm_kfree(&pdev->dev, lookup);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < data->desc_len; i++) {
+		dev_dbg(&pdev->dev, "con_id: '%s' idx: %d, flags: 0x%x\n",
+			data->desc[i].con_id, data->desc[i].idx,
+			data->desc[i].flags);
+		lookup->table[i].chip_label = label;
+		lookup->table[i].chip_hwnum = data->desc[i].idx;
+		lookup->table[i].idx = 0;
+		lookup->table[i].con_id = data->desc[i].con_id;
+		lookup->table[i].flags = data->desc[i].flags;
+	}
+
+	priv->lookup[cs] = lookup;
+	gpiod_add_lookup_table(lookup);
+	return 0;
+}
+
+static int ftdi_spi_probe(struct platform_device *pdev)
+{
+	const struct mpsse_spi_platform_data *pd;
+	struct device *dev = &pdev->dev;
+	struct spi_controller *master;
+	struct ftdi_spi *priv;
+	struct gpio_desc *desc;
+	u16 num_cs, max_cs = 0;
+	unsigned int i;
+	int ret;
+
+	pd = dev->platform_data;
+	if (!pd) {
+		dev_err(dev, "Missing platform data.\n");
+		return -EINVAL;
+	}
+
+	if (!pd->ops ||
+	    !pd->ops->read_data || !pd->ops->write_data ||
+	    !pd->ops->lock || !pd->ops->unlock ||
+	    !pd->ops->set_bitmode || !pd->ops->set_baudrate ||
+	    !pd->ops->disable_bitbang || !pd->ops->cfg_bus_pins)
+		return -EINVAL;
+
+	if (pd->spi_info_len > FTDI_MPSSE_GPIOS)
+		return -EINVAL;
+
+	/* Find max. slave chipselect number */
+	num_cs = pd->spi_info_len;
+	for (i = 0; i < num_cs; i++) {
+		if (max_cs < pd->spi_info[i].chip_select)
+			max_cs = pd->spi_info[i].chip_select;
+	}
+
+	if (max_cs > FTDI_MPSSE_GPIOS - 1) {
+		dev_err(dev, "Invalid max CS in platform data: %u\n", max_cs);
+		return -EINVAL;
+	}
+	dev_dbg(dev, "CS count %u, max CS %u\n", num_cs, max_cs);
+	max_cs += 1; /* including CS0 */
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*priv));
+	if (!master)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, master);
+
+	priv = spi_controller_get_devdata(master);
+	priv->master = master;
+	priv->pdev = pdev;
+	priv->intf = to_usb_interface(dev->parent);
+	priv->iops = pd->ops;
+
+	master->bus_num = -1;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP |
+			    SPI_CS_HIGH | SPI_LSB_FIRST;
+	master->num_chipselect = max_cs;
+	master->min_speed_hz = 450;
+	master->max_speed_hz = 30000000;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->set_cs = ftdi_spi_set_cs;
+	master->transfer_one = ftdi_spi_transfer_one;
+	master->auto_runtime_pm = false;
+
+	priv->cs_gpios = devm_kcalloc(&master->dev, max_cs, sizeof(desc),
+				      GFP_KERNEL);
+	if (!priv->cs_gpios) {
+		spi_controller_put(master);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < num_cs; i++) {
+		unsigned int idx = pd->spi_info[i].chip_select;
+
+		dev_dbg(&pdev->dev, "CS num: %u\n", idx);
+		desc = devm_gpiod_get_index(&priv->pdev->dev, "spi-cs",
+					    i, GPIOD_OUT_LOW);
+		if (IS_ERR(desc)) {
+			ret = PTR_ERR(desc);
+			dev_err(&pdev->dev, "CS %u gpiod err: %d\n", i, ret);
+			continue;
+		}
+		priv->cs_gpios[idx] = desc;
+	}
+
+	ret = spi_register_controller(master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register spi master\n");
+		spi_controller_put(master);
+		return ret;
+	}
+
+	ret = priv->iops->set_bitmode(priv->intf, 0x00, BITMODE_MPSSE);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to set MPSSE mode\n");
+		goto err;
+	}
+
+	priv->last_mode = 0xffff;
+
+	ret = ftdi_mpsse_init(priv);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "MPSSE init failed\n");
+		goto err;
+	}
+
+	for (i = 0; i < pd->spi_info_len; i++) {
+		struct spi_device *sdev;
+		u16 cs;
+
+		dev_dbg(&pdev->dev, "slave: '%s', CS: %u\n",
+			pd->spi_info[i].modalias, pd->spi_info[i].chip_select);
+
+		ret = ftdi_spi_init_io(master, i);
+		if (ret < 0) {
+			dev_warn(&pdev->dev, "Can't add slave IO: %d\n", ret);
+			continue;
+		}
+		sdev = spi_new_device(master, &pd->spi_info[i]);
+		if (!sdev) {
+			cs = pd->spi_info[i].chip_select;
+			dev_warn(&pdev->dev, "Can't add slave '%s', CS %u\n",
+				 pd->spi_info[i].modalias, cs);
+			if (priv->lookup[cs]) {
+				gpiod_remove_lookup_table(priv->lookup[cs]);
+				priv->lookup[cs] = NULL;
+			}
+		}
+	}
+
+	return 0;
+err:
+	platform_set_drvdata(pdev, NULL);
+	spi_unregister_controller(master);
+	return ret;
+}
+
+static int ftdi_spi_slave_release(struct device *dev, void *data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct ftdi_spi *priv = data;
+	u16 cs = spi->chip_select;
+
+	dev_dbg(dev, "%s: remove CS %u\n", __func__, cs);
+	spi_unregister_device(to_spi_device(dev));
+
+	if (priv->lookup[cs])
+		gpiod_remove_lookup_table(priv->lookup[cs]);
+	return 0;
+}
+
+static int ftdi_spi_remove(struct platform_device *pdev)
+{
+	struct spi_controller *master;
+	struct ftdi_spi *priv;
+
+	master = platform_get_drvdata(pdev);
+	priv = spi_controller_get_devdata(master);
+
+	device_for_each_child(&master->dev, priv, ftdi_spi_slave_release);
+
+	spi_unregister_controller(master);
+	return 0;
+}
+
+static struct platform_driver ftdi_spi_driver = {
+	.driver.name	= "ftdi-mpsse-spi",
+	.probe		= ftdi_spi_probe,
+	.remove		= ftdi_spi_remove,
+};
+module_platform_driver(ftdi_spi_driver);
+
+MODULE_ALIAS("platform:ftdi-mpsse-spi");
+MODULE_AUTHOR("Anatolij Gustschin <agust@...x.de");
+MODULE_DESCRIPTION("FTDI MPSSE SPI master driver");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1

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