Merge remote-tracking branches 'spi/topic/ath97', 'spi/topic/atmel', 'spi/topic/au1550', 'spi/topic/bcm2835' and 'spi/topic/bcm2835aux' into spi-next

Documentation/devicetree/bindings/spi/brcm,bcm2835-aux-spi.txt

@@ -0,0 +1,38 @@
+Broadcom BCM2835 auxiliar SPI1/2 controller
+
+The BCM2835 contains two forms of SPI master controller, one known simply as
+SPI0, and the other known as the "Universal SPI Master"; part of the
+auxiliary block. This binding applies to the SPI1/2 controller.
+
+Required properties:
+- compatible: Should be "brcm,bcm2835-aux-spi".
+- reg: Should contain register location and length for the spi block
+- interrupts: Should contain shared interrupt of the aux block
+- clocks: The clock feeding the SPI controller - needs to
+	  point to the auxiliar clock driver of the bcm2835,
+	  as this clock will enable the output gate for the specific
+	  clock.
+- cs-gpios: the cs-gpios (native cs is NOT supported)
+	    see also spi-bus.txt
+
+Example:
+
+spi1@7e215080 {
+	compatible = "brcm,bcm2835-aux-spi";
+	reg = <0x7e215080 0x40>;
+	interrupts = <1 29>;
+	clocks = <&aux_clocks BCM2835_AUX_CLOCK_SPI1>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	cs-gpios = <&gpio 18>, <&gpio 17>, <&gpio 16>;
+};
+
+spi2@7e2150c0 {
+	compatible = "brcm,bcm2835-aux-spi";
+	reg = <0x7e2150c0 0x40>;
+	interrupts = <1 29>;
+	clocks = <&aux_clocks BCM2835_AUX_CLOCK_SPI2>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	cs-gpios = <&gpio 43>, <&gpio 44>, <&gpio 45>;
+};

drivers/spi/Kconfig

@@ -88,6 +88,17 @@ config SPI_BCM2835
 	  is for the regular SPI controller. Slave mode operation is not also
 	  not supported.
 
+config SPI_BCM2835AUX
+	tristate "BCM2835 SPI auxiliary controller"
+	depends on ARCH_BCM2835 || COMPILE_TEST
+	depends on GPIOLIB
+	help
+	  This selects a driver for the Broadcom BCM2835 SPI aux master.
+
+	  The BCM2835 contains two types of SPI master controller; the
+	  "universal SPI master", and the regular SPI controller.
+	  This driver is for the universal/auxiliary SPI controller.
+
 config SPI_BFIN5XX
 	tristate "SPI controller driver for ADI Blackfin5xx"
 	depends on BLACKFIN && !BF60x

drivers/spi/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_SPI_ATMEL)			+= spi-atmel.o
 obj-$(CONFIG_SPI_ATH79)			+= spi-ath79.o
 obj-$(CONFIG_SPI_AU1550)		+= spi-au1550.o
 obj-$(CONFIG_SPI_BCM2835)		+= spi-bcm2835.o
+obj-$(CONFIG_SPI_BCM2835AUX)		+= spi-bcm2835aux.o
 obj-$(CONFIG_SPI_BCM53XX)		+= spi-bcm53xx.o
 obj-$(CONFIG_SPI_BCM63XX)		+= spi-bcm63xx.o
 obj-$(CONFIG_SPI_BCM63XX_HSSPI)		+= spi-bcm63xx-hsspi.o

drivers/spi/spi-ath79.c

@@ -240,14 +240,9 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	sp->bitbang.flags = SPI_CS_HIGH;
 
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (r == NULL) {
-		ret = -ENOENT;
-		goto err_put_master;
-	}
-
-	sp->base = devm_ioremap(&pdev->dev, r->start, resource_size(r));
-	if (!sp->base) {
-		ret = -ENXIO;
+	sp->base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(sp->base)) {
+		ret = PTR_ERR(sp->base);
 		goto err_put_master;
 	}
 

drivers/spi/spi-atmel.c

@@ -872,14 +872,7 @@ static int atmel_spi_set_xfer_speed(struct atmel_spi *as,
 	 * Calculate the lowest divider that satisfies the
 	 * constraint, assuming div32/fdiv/mbz == 0.
 	 */
-	if (xfer->speed_hz)
-		scbr = DIV_ROUND_UP(bus_hz, xfer->speed_hz);
-	else
-		/*
-		 * This can happend if max_speed is null.
-		 * In this case, we set the lowest possible speed
-		 */
-		scbr = 0xff;
+	scbr = DIV_ROUND_UP(bus_hz, xfer->speed_hz);
 
 	/*
 	 * If the resulting divider doesn't fit into the
@@ -1301,14 +1294,12 @@ static int atmel_spi_one_transfer(struct spi_master *master,
 		return -EINVAL;
 	}
 
-	if (xfer->bits_per_word) {
-		asd = spi->controller_state;
-		bits = (asd->csr >> 4) & 0xf;
-		if (bits != xfer->bits_per_word - 8) {
-			dev_dbg(&spi->dev,
+	asd = spi->controller_state;
+	bits = (asd->csr >> 4) & 0xf;
+	if (bits != xfer->bits_per_word - 8) {
+		dev_dbg(&spi->dev,
 			"you can't yet change bits_per_word in transfers\n");
-			return -ENOPROTOOPT;
-		}
+		return -ENOPROTOOPT;
 	}
 
 	/*

drivers/spi/spi-au1550.c

@@ -233,13 +233,12 @@ static int au1550_spi_setupxfer(struct spi_device *spi, struct spi_transfer *t)
 	unsigned bpw, hz;
 	u32 cfg, stat;
 
-	bpw = spi->bits_per_word;
-	hz = spi->max_speed_hz;
 	if (t) {
-		if (t->bits_per_word)
-			bpw = t->bits_per_word;
-		if (t->speed_hz)
-			hz = t->speed_hz;
+		bpw = t->bits_per_word;
+		hz = t->speed_hz;
+	} else {
+		bpw = spi->bits_per_word;
+		hz = spi->max_speed_hz;
 	}
 
 	if (!hz)

drivers/spi/spi-bcm2835.c

@@ -777,7 +777,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
 		goto out_master_put;
 	}
 
-	bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+	bs->irq = platform_get_irq(pdev, 0);
 	if (bs->irq <= 0) {
 		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
 		err = bs->irq ? bs->irq : -ENODEV;
@@ -786,6 +786,12 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
 
 	clk_prepare_enable(bs->clk);
 
+	bcm2835_dma_init(master, &pdev->dev);
+
+	/* initialise the hardware with the default polarities */
+	bcm2835_wr(bs, BCM2835_SPI_CS,
+		   BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+
 	err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0,
 			       dev_name(&pdev->dev), master);
 	if (err) {
@@ -793,12 +799,6 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
 		goto out_clk_disable;
 	}
 
-	bcm2835_dma_init(master, &pdev->dev);
-
-	/* initialise the hardware with the default polarities */
-	bcm2835_wr(bs, BCM2835_SPI_CS,
-		   BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
-
 	err = devm_spi_register_master(&pdev->dev, master);
 	if (err) {
 		dev_err(&pdev->dev, "could not register SPI master: %d\n", err);

drivers/spi/spi-bcm2835aux.c

@@ -0,0 +1,512 @@
+/*
+ * Driver for Broadcom BCM2835 auxiliary SPI Controllers
+ *
+ * the driver does not rely on the native chipselects at all
+ * but only uses the gpio type chipselects
+ *
+ * Based on: spi-bcm2835.c
+ *
+ * Copyright (C) 2015 Martin Sperl
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/spinlock.h>
+
+/*
+ * spi register defines
+ *
+ * note there is garbage in the "official" documentation,
+ * so some data is taken from the file:
+ *   brcm_usrlib/dag/vmcsx/vcinclude/bcm2708_chip/aux_io.h
+ * inside of:
+ *   http://www.broadcom.com/docs/support/videocore/Brcm_Android_ICS_Graphics_Stack.tar.gz
+ */
+
+/* SPI register offsets */
+#define BCM2835_AUX_SPI_CNTL0	0x00
+#define BCM2835_AUX_SPI_CNTL1	0x04
+#define BCM2835_AUX_SPI_STAT	0x08
+#define BCM2835_AUX_SPI_PEEK	0x0C
+#define BCM2835_AUX_SPI_IO	0x20
+#define BCM2835_AUX_SPI_TXHOLD	0x30
+
+/* Bitfields in CNTL0 */
+#define BCM2835_AUX_SPI_CNTL0_SPEED	0xFFF00000
+#define BCM2835_AUX_SPI_CNTL0_SPEED_MAX	0xFFF
+#define BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT	20
+#define BCM2835_AUX_SPI_CNTL0_CS	0x000E0000
+#define BCM2835_AUX_SPI_CNTL0_POSTINPUT	0x00010000
+#define BCM2835_AUX_SPI_CNTL0_VAR_CS	0x00008000
+#define BCM2835_AUX_SPI_CNTL0_VAR_WIDTH	0x00004000
+#define BCM2835_AUX_SPI_CNTL0_DOUTHOLD	0x00003000
+#define BCM2835_AUX_SPI_CNTL0_ENABLE	0x00000800
+#define BCM2835_AUX_SPI_CNTL0_CPHA_IN	0x00000400
+#define BCM2835_AUX_SPI_CNTL0_CLEARFIFO	0x00000200
+#define BCM2835_AUX_SPI_CNTL0_CPHA_OUT	0x00000100
+#define BCM2835_AUX_SPI_CNTL0_CPOL	0x00000080
+#define BCM2835_AUX_SPI_CNTL0_MSBF_OUT	0x00000040
+#define BCM2835_AUX_SPI_CNTL0_SHIFTLEN	0x0000003F
+
+/* Bitfields in CNTL1 */
+#define BCM2835_AUX_SPI_CNTL1_CSHIGH	0x00000700
+#define BCM2835_AUX_SPI_CNTL1_IDLE	0x00000080
+#define BCM2835_AUX_SPI_CNTL1_TXEMPTY	0x00000040
+#define BCM2835_AUX_SPI_CNTL1_MSBF_IN	0x00000002
+#define BCM2835_AUX_SPI_CNTL1_KEEP_IN	0x00000001
+
+/* Bitfields in STAT */
+#define BCM2835_AUX_SPI_STAT_TX_LVL	0xFF000000
+#define BCM2835_AUX_SPI_STAT_RX_LVL	0x00FF0000
+#define BCM2835_AUX_SPI_STAT_TX_FULL	0x00000400
+#define BCM2835_AUX_SPI_STAT_TX_EMPTY	0x00000200
+#define BCM2835_AUX_SPI_STAT_RX_FULL	0x00000100
+#define BCM2835_AUX_SPI_STAT_RX_EMPTY	0x00000080
+#define BCM2835_AUX_SPI_STAT_BUSY	0x00000040
+#define BCM2835_AUX_SPI_STAT_BITCOUNT	0x0000003F
+
+/* timeout values */
+#define BCM2835_AUX_SPI_POLLING_LIMIT_US	30
+#define BCM2835_AUX_SPI_POLLING_JIFFIES		2
+
+#define BCM2835_AUX_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
+				  | SPI_NO_CS)
+
+struct bcm2835aux_spi {
+	void __iomem *regs;
+	struct clk *clk;
+	int irq;
+	u32 cntl[2];
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	int tx_len;
+	int rx_len;
+	int pending;
+};
+
+static inline u32 bcm2835aux_rd(struct bcm2835aux_spi *bs, unsigned reg)
+{
+	return readl(bs->regs + reg);
+}
+
+static inline void bcm2835aux_wr(struct bcm2835aux_spi *bs, unsigned reg,
+				 u32 val)
+{
+	writel(val, bs->regs + reg);
+}
+
+static inline void bcm2835aux_rd_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	int count = min(bs->rx_len, 3);
+
+	data = bcm2835aux_rd(bs, BCM2835_AUX_SPI_IO);
+	if (bs->rx_buf) {
+		switch (count) {
+		case 4:
+			*bs->rx_buf++ = (data >> 24) & 0xff;
+			/* fallthrough */
+		case 3:
+			*bs->rx_buf++ = (data >> 16) & 0xff;
+			/* fallthrough */
+		case 2:
+			*bs->rx_buf++ = (data >> 8) & 0xff;
+			/* fallthrough */
+		case 1:
+			*bs->rx_buf++ = (data >> 0) & 0xff;
+			/* fallthrough - no default */
+		}
+	}
+	bs->rx_len -= count;
+	bs->pending -= count;
+}
+
+static inline void bcm2835aux_wr_fifo(struct bcm2835aux_spi *bs)
+{
+	u32 data;
+	u8 byte;
+	int count;
+	int i;
+
+	/* gather up to 3 bytes to write to the FIFO */
+	count = min(bs->tx_len, 3);
+	data = 0;
+	for (i = 0; i < count; i++) {
+		byte = bs->tx_buf ? *bs->tx_buf++ : 0;
+		data |= byte << (8 * (2 - i));
+	}
+
+	/* and set the variable bit-length */
+	data |= (count * 8) << 24;
+
+	/* and decrement length */
+	bs->tx_len -= count;
+	bs->pending += count;
+
+	/* write to the correct TX-register */
+	if (bs->tx_len)
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_TXHOLD, data);
+	else
+		bcm2835aux_wr(bs, BCM2835_AUX_SPI_IO, data);
+}
+
+static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs)
+{
+	/* disable spi clearing fifo and interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, 0);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0,
+		      BCM2835_AUX_SPI_CNTL0_CLEARFIFO);
+}
+
+static irqreturn_t bcm2835aux_spi_interrupt(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	irqreturn_t ret = IRQ_NONE;
+
+	/* check if we have data to read */
+	while (bs->rx_len &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_RX_EMPTY))) {
+		bcm2835aux_rd_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* check if we have data to write */
+	while (bs->tx_len &&
+	       (bs->pending < 12) &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* and check if we have reached "done" */
+	while (bs->rx_len &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_BUSY))) {
+		bcm2835aux_rd_fifo(bs);
+		ret = IRQ_HANDLED;
+	}
+
+	/* and if rx_len is 0 then wake up completion and disable spi */
+	if (!bs->rx_len) {
+		bcm2835aux_spi_reset_hw(bs);
+		complete(&master->xfer_completion);
+	}
+
+	/* and return */
+	return ret;
+}
+
+static int __bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					     struct spi_device *spi,
+					     struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* enable interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1] |
+		BCM2835_AUX_SPI_CNTL1_TXEMPTY |
+		BCM2835_AUX_SPI_CNTL1_IDLE);
+
+	/* and wait for finish... */
+	return 1;
+}
+
+static int bcm2835aux_spi_transfer_one_irq(struct spi_master *master,
+					   struct spi_device *spi,
+					   struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	/* fill in registers and fifos before enabling interrupts */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* fill in tx fifo with data before enabling interrupts */
+	while ((bs->tx_len) &&
+	       (bs->pending < 12) &&
+	       (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) &
+		  BCM2835_AUX_SPI_STAT_TX_FULL))) {
+		bcm2835aux_wr_fifo(bs);
+	}
+
+	/* now run the interrupt mode */
+	return __bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+}
+
+static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master,
+					    struct spi_device *spi,
+					struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long timeout;
+	u32 stat;
+
+	/* configure spi */
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
+	bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
+
+	/* set the timeout */
+	timeout = jiffies + BCM2835_AUX_SPI_POLLING_JIFFIES;
+
+	/* loop until finished the transfer */
+	while (bs->rx_len) {
+		/* read status */
+		stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT);
+
+		/* fill in tx fifo with remaining data */
+		if ((bs->tx_len) && (!(stat & BCM2835_AUX_SPI_STAT_TX_FULL))) {
+			bcm2835aux_wr_fifo(bs);
+			continue;
+		}
+
+		/* read data from fifo for both cases */
+		if (!(stat & BCM2835_AUX_SPI_STAT_RX_EMPTY)) {
+			bcm2835aux_rd_fifo(bs);
+			continue;
+		}
+		if (!(stat & BCM2835_AUX_SPI_STAT_BUSY)) {
+			bcm2835aux_rd_fifo(bs);
+			continue;
+		}
+
+		/* there is still data pending to read check the timeout */
+		if (bs->rx_len && time_after(jiffies, timeout)) {
+			dev_dbg_ratelimited(&spi->dev,
+					    "timeout period reached: jiffies: %lu remaining tx/rx: %d/%d - falling back to interrupt mode\n",
+					    jiffies - timeout,
+					    bs->tx_len, bs->rx_len);
+			/* forward to interrupt handler */
+			return __bcm2835aux_spi_transfer_one_irq(master,
+							       spi, tfr);
+		}
+	}
+
+	/* Transfer complete - reset SPI HW */
+	bcm2835aux_spi_reset_hw(bs);
+
+	/* and return without waiting for completion */
+	return 0;
+}
+
+static int bcm2835aux_spi_transfer_one(struct spi_master *master,
+				       struct spi_device *spi,
+				       struct spi_transfer *tfr)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+	unsigned long spi_hz, clk_hz, speed;
+	unsigned long spi_used_hz;
+	unsigned long long xfer_time_us;
+
+	/* calculate the registers to handle
+	 *
+	 * note that we use the variable data mode, which
+	 * is not optimal for longer transfers as we waste registers
+	 * resulting (potentially) in more interrupts when transferring
+	 * more than 12 bytes
+	 */
+	bs->cntl[0] = BCM2835_AUX_SPI_CNTL0_ENABLE |
+		      BCM2835_AUX_SPI_CNTL0_VAR_WIDTH |
+		      BCM2835_AUX_SPI_CNTL0_MSBF_OUT;
+	bs->cntl[1] = BCM2835_AUX_SPI_CNTL1_MSBF_IN;
+
+	/* set clock */
+	spi_hz = tfr->speed_hz;
+	clk_hz = clk_get_rate(bs->clk);
+
+	if (spi_hz >= clk_hz / 2) {
+		speed = 0;
+	} else if (spi_hz) {
+		speed = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
+		if (speed >  BCM2835_AUX_SPI_CNTL0_SPEED_MAX)
+			speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	} else { /* the slowest we can go */
+		speed = BCM2835_AUX_SPI_CNTL0_SPEED_MAX;
+	}
+	bs->cntl[0] |= speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT;
+
+	spi_used_hz = clk_hz / (2 * (speed + 1));
+
+	/* handle all the modes */
+	if (spi->mode & SPI_CPOL)
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPOL;
+	if (spi->mode & SPI_CPHA)
+		bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPHA_OUT |
+			       BCM2835_AUX_SPI_CNTL0_CPHA_IN;
+
+	/* set transmit buffers and length */
+	bs->tx_buf = tfr->tx_buf;
+	bs->rx_buf = tfr->rx_buf;
+	bs->tx_len = tfr->len;
+	bs->rx_len = tfr->len;
+	bs->pending = 0;
+
+	/* calculate the estimated time in us the transfer runs
+	 * note that there are are 2 idle clocks after each
+	 * chunk getting transferred - in our case the chunk size
+	 * is 3 bytes, so we approximate this by 9 bits/byte
+	 */
+	xfer_time_us = tfr->len * 9 * 1000000;
+	do_div(xfer_time_us, spi_used_hz);
+
+	/* run in polling mode for short transfers */
+	if (xfer_time_us < BCM2835_AUX_SPI_POLLING_LIMIT_US)
+		return bcm2835aux_spi_transfer_one_poll(master, spi, tfr);
+
+	/* run in interrupt mode for all others */
+	return bcm2835aux_spi_transfer_one_irq(master, spi, tfr);
+}
+
+static void bcm2835aux_spi_handle_err(struct spi_master *master,
+				      struct spi_message *msg)
+{
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+}
+
+static int bcm2835aux_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct bcm2835aux_spi *bs;
+	struct resource *res;
+	unsigned long clk_hz;
+	int err;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*bs));
+	if (!master) {
+		dev_err(&pdev->dev, "spi_alloc_master() failed\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, master);
+	master->mode_bits = BCM2835_AUX_SPI_MODE_BITS;
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
+	master->num_chipselect = -1;
+	master->transfer_one = bcm2835aux_spi_transfer_one;
+	master->handle_err = bcm2835aux_spi_handle_err;
+	master->dev.of_node = pdev->dev.of_node;
+
+	bs = spi_master_get_devdata(master);
+
+	/* the main area */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bs->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(bs->regs)) {
+		err = PTR_ERR(bs->regs);
+		goto out_master_put;
+	}
+
+	bs->clk = devm_clk_get(&pdev->dev, NULL);
+	if ((!bs->clk) || (IS_ERR(bs->clk))) {
+		err = PTR_ERR(bs->clk);
+		dev_err(&pdev->dev, "could not get clk: %d\n", err);
+		goto out_master_put;
+	}
+
+	bs->irq = platform_get_irq(pdev, 0);
+	if (bs->irq <= 0) {
+		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
+		err = bs->irq ? bs->irq : -ENODEV;
+		goto out_master_put;
+	}
+
+	/* this also enables the HW block */
+	err = clk_prepare_enable(bs->clk);
+	if (err) {
+		dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
+		goto out_master_put;
+	}
+
+	/* just checking if the clock returns a sane value */
+	clk_hz = clk_get_rate(bs->clk);
+	if (!clk_hz) {
+		dev_err(&pdev->dev, "clock returns 0 Hz\n");
+		err = -ENODEV;
+		goto out_clk_disable;
+	}
+
+	/* reset SPI-HW block */
+	bcm2835aux_spi_reset_hw(bs);
+
+	err = devm_request_irq(&pdev->dev, bs->irq,
+			       bcm2835aux_spi_interrupt,
+			       IRQF_SHARED,
+			       dev_name(&pdev->dev), master);
+	if (err) {
+		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err) {
+		dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
+		goto out_clk_disable;
+	}
+
+	return 0;
+
+out_clk_disable:
+	clk_disable_unprepare(bs->clk);
+out_master_put:
+	spi_master_put(master);
+	return err;
+}
+
+static int bcm2835aux_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
+
+	bcm2835aux_spi_reset_hw(bs);
+
+	/* disable the HW block by releasing the clock */
+	clk_disable_unprepare(bs->clk);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835aux_spi_match[] = {
+	{ .compatible = "brcm,bcm2835-aux-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, bcm2835aux_spi_match);
+
+static struct platform_driver bcm2835aux_spi_driver = {
+	.driver		= {
+		.name		= "spi-bcm2835aux",
+		.of_match_table	= bcm2835aux_spi_match,
+	},
+	.probe		= bcm2835aux_spi_probe,
+	.remove		= bcm2835aux_spi_remove,
+};
+module_platform_driver(bcm2835aux_spi_driver);
+
+MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835 aux");
+MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
+MODULE_LICENSE("GPL v2");