Patchwork Subject: [PATCH v7] spi: Add PPC4xx SPI driver

login
register
mail settings
Submitter Steven A. Falco
Date June 25, 2009, 7:12 p.m.
Message ID <4A43CC2C.1030409@harris.com>
Download mbox | patch
Permalink /patch/29182/
State Superseded
Headers show

Comments

Steven A. Falco - June 25, 2009, 7:12 p.m.
This adds a SPI driver for the SPI controller found in the IBM/AMCC
4xx PowerPC's.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Wolfgang Ocker <weo@reccoware.de>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Steven A. Falco <sfalco@harris.com>
---
Note, I have not removed any of the prior sign-offs, but feel free to
look this version over very closely, and let me know if you demand a
"retraction".  :-)

I've successfully used this driver on a custom PPC440EPx based board
with three devices on the spi bus, one of which uses the "chip-select
hole" feature.

Changes in v7:
- Additional comments as per David Brownell's review
- Corrected phase in mode 2 and 3
- Corrected speed and bits_per_word logic in spi_ppc4xx_setupxfer
- Removed extraneous tests as per David's review
- Added support for "holes" in the chip-select list
- Using dynamic bus allocation
- Corrected initialization logic

Changes in v6:
- Moved comment about high interrupt load to top of file and extended it
  by explaining that the 4xx SPI controller has no FIFOs.
- Added parameter checking to setup() routine.
- Removed comment about LSB
- Used of_gpio_count() instead creating own static implementation as
  suggested by Anton.

Changes in v5:
- Don't call setupxfer() from setup() so that the baudrate etc
  won't get changed while another transfer is active, as suggested
  by David Brownell.
- module_{init,exit} moved directly to the functions to which they
  apply.
- Use __func__ instead of __FUNCTION__.

Changes in v4:
- Added fixes suggested by Josh Boyer
- Changed compatible property from "ibm,spi" to "ibm,ppc4xx-spi"

Changes in v3:
- When the device is removed the GPIOs are released. The memory
  for the GPIO array is freed.

Changes in v2:
- Now the gpios property is correctly decoded and the
  resulting gpio numbers are used as the devices chip
  selects.
David Brownell - June 26, 2009, 4:04 a.m.
On Thursday 25 June 2009, Steven A. Falco wrote:
> +       if (spi->mode & ~MODEBITS) {
> +               dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
> +                       spi->mode & ~MODEBITS);
> +               return -EINVAL;
> +       }

This wasn't tested against 2.6.30-rc1 was it?

See the recent fixup patch I sent.  There's a spi_master->modebits
mask that should have been initialized, and which eliminates the
need for tests like that ...

> +       dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
> +               __func__, spi->mode, spi->bits_per_word,
> +               spi->max_speed_hz);
> +

... also the SPI core now provides a *standard* format debug
message for that stuff.  It also handles one more thing, which
I expect to see fixed in a v8 of this patch ... :)

- Dave
Steven A. Falco - June 26, 2009, 4:17 p.m.
David Brownell wrote:
> On Thursday 25 June 2009, Steven A. Falco wrote:
>> +       if (spi->mode & ~MODEBITS) {
>> +               dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
>> +                       spi->mode & ~MODEBITS);
>> +               return -EINVAL;
>> +       }
> 
> This wasn't tested against 2.6.30-rc1 was it?
> 

I tested against Ben's "next" branch, plus your fix for bitbang_work.
But the new version I'll post is tested against Linus' master branch
(2.6.31-rc1) to take advantage of your mode_bits addition.  If you need
this driver to be based on something else, please say so.

> See the recent fixup patch I sent.  There's a spi_master->modebits
> mask that should have been initialized, and which eliminates the
> need for tests like that ...
> 

Done.

>> +       dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
>> +               __func__, spi->mode, spi->bits_per_word,
>> +               spi->max_speed_hz);
>> +
> 
> ... also the SPI core now provides a *standard* format debug
> message for that stuff.  It also handles one more thing, which
> I expect to see fixed in a v8 of this patch ...  :) 

Ok - I removed that dev_dbg().  Also, I noticed that spi_setup sets
bits_per_word to 8, so I've removed that as well.  Did I pass your
test?  :-) 

Version 8 will follow shortly.  BTW, this driver is dependent on your
bitbang_work fix.  Not sure if that means it should be added via your
tree.  But since we are in an rc phase, I'm guessing this won't merge
until 2.6.32, by which time your fix should be in the mainline.

	Steve

Patch

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 83a185d..2f0a3df 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -171,6 +171,13 @@  config SPI_ORION
 	help
 	  This enables using the SPI master controller on the Orion chips.
 
+config SPI_PPC4xx
+	tristate "PPC4xx SPI Controller"
+	depends on 4xx && SPI_MASTER
+	select SPI_BITBANG
+	help
+	  This selects a driver for the PPC4xx SPI Controller.
+
 config SPI_PXA2XX
 	tristate "PXA2xx SSP SPI master"
 	depends on ARCH_PXA && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 5d04519..ed1d74f 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -23,8 +23,9 @@  obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
 obj-$(CONFIG_SPI_OMAP_UWIRE)		+= omap_uwire.o
 obj-$(CONFIG_SPI_OMAP24XX)		+= omap2_mcspi.o
 obj-$(CONFIG_SPI_ORION)			+= orion_spi.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)		+= mpc52xx_psc_spi.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
+obj-$(CONFIG_SPI_PPC4xx)		+= spi_ppc4xx.o
 obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi_s3c24xx.o
 obj-$(CONFIG_SPI_TXX9)			+= spi_txx9.o
diff --git a/drivers/spi/spi_ppc4xx.c b/drivers/spi/spi_ppc4xx.c
new file mode 100644
index 0000000..631bca2
--- /dev/null
+++ b/drivers/spi/spi_ppc4xx.c
@@ -0,0 +1,623 @@ 
+/*
+ * SPI_PPC4XX SPI controller driver.
+ *
+ * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de>
+ * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering
+ * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com>
+ *
+ * Based in part on drivers/spi/spi_s3c24xx.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+/*
+ * The PPC4xx SPI controller has no FIFO so each sent/received byte will
+ * generate an interrupt to the CPU. This can cause high CPU utilization.
+ * This driver allows platforms to reduce the interrupt load on the CPU
+ * during SPI transfers by setting max_speed_hz via the device tree.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/of_platform.h>
+#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/io.h>
+#include <asm/dcr.h>
+#include <asm/dcr-regs.h>
+
+/* bits in mode register - bit 0 is MSb */
+
+/*
+ * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock"
+ * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock"
+ * Note: This is the inverse of CPHA.
+ */
+#define SPI_PPC4XX_MODE_SCP	(0x80 >> 3)
+
+/* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */
+#define SPI_PPC4XX_MODE_SPE	(0x80 >> 4)
+
+/*
+ * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode
+ * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode
+ * Note: This is identical to SPI_LSB_FIRST.
+ */
+#define SPI_PPC4XX_MODE_RD	(0x80 >> 5)
+
+/*
+ * SPI_PPC4XX_MODE_CI = 0 means "clock idles low"
+ * SPI_PPC4XX_MODE_CI = 1 means "clock idles high"
+ * Note: This is identical to CPOL.
+ */
+#define SPI_PPC4XX_MODE_CI	(0x80 >> 6)
+
+/*
+ * SPI_PPC4XX_MODE_IL = 0 means "loopback disable"
+ * SPI_PPC4XX_MODE_IL = 1 means "loopback enable"
+ */
+#define SPI_PPC4XX_MODE_IL	(0x80 >> 7)
+
+/* bits in control register */
+/* starts a transfer when set */
+#define SPI_PPC4XX_CR_STR	(0x80 >> 7)
+
+/* bits in status register */
+/* port is busy with a transfer */
+#define SPI_PPC4XX_SR_BSY	(0x80 >> 6)
+/* RxD ready */
+#define SPI_PPC4XX_SR_RBR	(0x80 >> 7)
+
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS	(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST)
+
+/* clock settings (SCP and CI) for various SPI modes */
+#define SPI_CLK_MODE0	(SPI_PPC4XX_MODE_SCP | 0)
+#define SPI_CLK_MODE1	(0 | 0)
+#define SPI_CLK_MODE2	(SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
+#define SPI_CLK_MODE3	(0 | SPI_PPC4XX_MODE_CI)
+
+#define DRIVER_NAME	"spi_ppc4xx_of"
+
+struct spi_ppc4xx_regs {
+	u8 mode;
+	u8 rxd;
+	u8 txd;
+	u8 cr;
+	u8 sr;
+	u8 dummy;
+	/*
+	 * Clock divisor modulus register
+	 * This uses the follwing formula:
+	 *    SCPClkOut = OPBCLK/(4(CDM + 1))
+	 * or
+	 *    CDM = (OPBCLK/4*SCPClkOut) - 1
+	 * bit 0 is the MSb!
+	 */
+	u8 cdm;
+};
+
+/* SPI Controller driver's private data. */
+struct ppc4xx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	u64 mapbase;
+	u64 mapsize;
+	int irqnum;
+	/* need this to set the SPI clock */
+	unsigned int opb_freq;
+
+	/* for transfers */
+	int len;
+	int count;
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+
+	int *gpios;
+
+	struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
+	struct spi_master *master;
+	struct device *dev;
+};
+
+/* need this so we can set the clock in the chipselect routine */
+struct spi_ppc4xx_cs {
+	u8 mode;
+};
+
+static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw;
+	u8 data;
+
+	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+		t->tx_buf, t->rx_buf, t->len);
+
+	hw = spi_master_get_devdata(spi->master);
+
+	hw->tx = t->tx_buf;
+	hw->rx = t->rx_buf;
+	hw->len = t->len;
+	hw->count = 0;
+
+	/* send the first byte */
+	data = hw->tx ? hw->tx[0] : 0;
+	out_8(&hw->regs->txd, data);
+	out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	wait_for_completion(&hw->done);
+
+	return hw->count;
+}
+
+static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+	int scr;
+	u8 cdm = 0;
+	u32 speed;
+	u8 bits_per_word;
+
+ 	/* Start with the generic configuration for this device. */
+	bits_per_word = spi->bits_per_word;
+	speed = spi->max_speed_hz;
+
+	/*
+	 * Modify the configuration if the transfer overrides it.  Do not allow
+	 * the transfer to overwrite the generic configuration with zeros.
+	 */
+	if (t) {
+		if (t->bits_per_word)
+			bits_per_word = t->bits_per_word;
+
+		if (t->speed_hz)
+			speed = min(t->speed_hz, spi->max_speed_hz);
+	}
+
+	if (bits_per_word != 8) {
+		dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bits_per_word);
+		return -EINVAL;
+	}
+
+	if (!speed || (speed > spi->max_speed_hz)) {
+		dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
+		return -EINVAL;
+	}
+
+	/* Write new configration */
+	out_8(&hw->regs->mode, cs->mode);
+
+	/* Set the clock */
+	/* opb_freq was already divided by 4 */
+	scr = (hw->opb_freq / speed) - 1;
+	if (scr > 0)
+		cdm = min(scr, 0xff);
+
+	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
+
+	if (in_8(&hw->regs->cdm) != cdm)
+		out_8(&hw->regs->cdm, cdm);
+
+	spin_lock(&hw->bitbang.lock);
+	if (!hw->bitbang.busy) {
+		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+		/* Need to ndelay here? */
+	}
+	spin_unlock(&hw->bitbang.lock);
+
+	return 0;
+}
+
+static int spi_ppc4xx_setup(struct spi_device *spi)
+{
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	if (spi->bits_per_word != 8) {
+		dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
+			spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	if (!spi->max_speed_hz) {
+		dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
+		return -EINVAL;
+	}
+
+	if (spi->mode & ~MODEBITS) {
+		dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+			spi->mode & ~MODEBITS);
+		return -EINVAL;
+	}
+
+	if (cs == NULL) {
+		cs = kzalloc(sizeof *cs, GFP_KERNEL);
+		if (!cs)
+			return -ENOMEM;
+		spi->controller_state = cs;
+	}
+
+	/*
+	 * We set all bits of the SPI0_MODE register, so,
+	 * no need to read-modify-write
+	 */
+	cs->mode = SPI_PPC4XX_MODE_SPE;
+
+	switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
+	case SPI_MODE_0:
+		cs->mode |= SPI_CLK_MODE0;
+		break;
+	case SPI_MODE_1:
+		cs->mode |= SPI_CLK_MODE1;
+		break;
+	case SPI_MODE_2:
+		cs->mode |= SPI_CLK_MODE2;
+		break;
+	case SPI_MODE_3:
+		cs->mode |= SPI_CLK_MODE3;
+		break;
+	}
+
+	if (spi->mode & SPI_LSB_FIRST)
+		cs->mode |= SPI_PPC4XX_MODE_RD;
+
+	dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
+		__func__, spi->mode, spi->bits_per_word,
+		spi->max_speed_hz);
+
+	return 0;
+}
+
+static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
+{
+	struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+	unsigned int cs = spi->chip_select;
+	unsigned int cspol;
+
+	/*
+	 * If there are no chip selects at all, or if this is the special case of
+	 * a non-existent (dummy) chip select, do nothing.
+	 */
+
+	if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST)
+		return;
+
+	cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+	if (value == BITBANG_CS_INACTIVE)
+		cspol = !cspol;
+
+	gpio_set_value(hw->gpios[cs], cspol);
+}
+
+static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
+{
+	struct ppc4xx_spi *hw;
+	u8 status;
+	u8 data;
+	unsigned int count;
+
+	hw = (struct ppc4xx_spi *)dev_id;
+
+	status = in_8(&hw->regs->sr);
+	if (!status)
+		return IRQ_NONE;
+
+	/*
+	 * BSY de-asserts one cycle after the transfer is complete.  The interrupt
+	 * is asserted after the transfer is complete.  The exact relationship is
+	 * not documented, hence this code.
+	 */
+
+	if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
+		u8 lstatus;
+		int cnt = 0;
+
+		dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
+		do {
+			ndelay(10);
+			lstatus = in_8(&hw->regs->sr);
+		} while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
+
+		if (cnt >= 100) {
+			dev_err(hw->dev, "busywait: too many loops!\n");
+			complete(&hw->done);
+			return IRQ_HANDLED;
+		} else {
+			/* status is always 1 (RBR) here */
+			status = in_8(&hw->regs->sr);
+			dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
+		}
+	}
+
+	count = hw->count;
+	hw->count++;
+
+	/* RBR triggered this interrupt.  Therefore, data must be ready. */
+	data = in_8(&hw->regs->rxd);
+	if (hw->rx)
+		hw->rx[count] = data;
+
+	count++;
+
+	if (count < hw->len) {
+		data = hw->tx ? hw->tx[count] : 0;
+		out_8(&hw->regs->txd, data);
+		out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	} else {
+		complete(&hw->done);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void spi_ppc4xx_cleanup(struct spi_device *spi)
+{
+	kfree(spi->controller_state);
+}
+
+static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
+{
+	/*
+	 * On all 4xx PPC's the SPI bus is shared/multiplexed with
+	 * the 2nd I2C bus. We need to enable the the SPI bus before
+	 * using it.
+	 */
+
+	/* need to clear bit 14 to enable SPC */
+	dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
+}
+
+static void free_gpios(struct ppc4xx_spi *hw)
+{
+	if (hw->master->num_chipselect) {
+		int i;
+		for (i = 0; i < hw->master->num_chipselect; i++)
+			if (gpio_is_valid(hw->gpios[i]))
+				gpio_free(hw->gpios[i]);
+
+		kfree(hw->gpios);
+		hw->gpios = NULL;
+	}
+}
+
+/*
+ * of_device layer stuff...
+ */
+static int __init spi_ppc4xx_of_probe(struct of_device *op,
+				      const struct of_device_id *match)
+{
+	struct ppc4xx_spi *hw;
+	struct spi_master *master;
+	struct spi_bitbang *bbp;
+	struct resource resource;
+	struct device_node *np = op->node;
+	struct device *dev = &op->dev;
+	struct device_node *opbnp;
+	int ret;
+	int num_gpios;
+	const unsigned int *clk;
+
+	master = spi_alloc_master(dev, sizeof *hw);
+	if (master == NULL)
+		return -ENOMEM;
+	dev_set_drvdata(dev, master);
+	hw = spi_master_get_devdata(master);
+	hw->master = spi_master_get(master);
+	hw->dev = dev;
+
+	init_completion(&hw->done);
+
+	/*
+	 * A count of zero implies a single SPI device without any chip-select.
+	 * Note that of_gpio_count counts all gpios assigned to this spi master.
+	 * This includes both "null" gpio's and real ones.
+	 */
+	num_gpios = of_gpio_count(np);
+	if (num_gpios) {
+		int i;
+
+		hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
+		if (!hw->gpios) {
+			ret = -ENOMEM;
+			goto free_master;
+		}
+
+		for (i = 0; i < num_gpios; i++) {
+			int gpio;
+			enum of_gpio_flags flags;
+		       
+			gpio = of_get_gpio_flags(np, i, &flags);
+			hw->gpios[i] = gpio;
+
+			if (gpio_is_valid(gpio)) {
+				/* Real CS - set the initial state. */
+				ret = gpio_request(gpio, np->name);
+				if (ret < 0) {
+					dev_err(dev, "can't request gpio #%d: %d\n",
+							i, ret);
+					goto free_gpios;
+				}
+
+				gpio_direction_output(gpio,
+						!!(flags & OF_GPIO_ACTIVE_LOW));
+			} else if (gpio == -EEXIST) {
+				; /* No CS, but that's OK. */
+			} else {
+				dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
+				ret = -EINVAL;
+				goto free_gpios;
+			}
+		}
+	}
+
+	/* Setup the state for the bitbang driver */
+	bbp = &hw->bitbang;
+	bbp->master = hw->master;
+	bbp->setup_transfer = spi_ppc4xx_setupxfer;
+	bbp->chipselect = spi_ppc4xx_chipsel;
+	bbp->txrx_bufs = spi_ppc4xx_txrx;
+	bbp->use_dma = 0;
+	bbp->master->setup = spi_ppc4xx_setup;
+	bbp->master->cleanup = spi_ppc4xx_cleanup;
+
+	/* Allocate bus num dynamically. */
+	bbp->master->bus_num = -1;
+
+	/* this many pins in all GPIO controllers */
+	bbp->master->num_chipselect = num_gpios;
+
+	/* Get the clock for the OPB */
+	opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
+	if (opbnp == NULL) {
+		dev_err(dev, "OPB: cannot find node\n");
+		ret = -ENODEV;
+		goto free_gpios;
+	}
+	/* Get the clock (Hz) for the OPB */
+	clk = of_get_property(opbnp, "clock-frequency", NULL);
+	if (clk == NULL) {
+		dev_err(dev, "OPB: no clock-frequency property set\n");
+		of_node_put(opbnp);
+		ret = -ENODEV;
+		goto free_gpios;
+	}
+	hw->opb_freq = *clk;
+	hw->opb_freq >>= 2;
+	of_node_put(opbnp);
+
+	ret = of_address_to_resource(np, 0, &resource);
+	if (ret) {
+		dev_err(dev, "error while parsing device node resource\n");
+		goto free_gpios;
+	}
+	hw->mapbase = resource.start;
+	hw->mapsize = resource.end - resource.start + 1;
+
+	/* Sanity check */
+	if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
+		dev_err(dev, "too small to map registers\n");
+		ret = -EINVAL;
+		goto free_gpios;
+	}
+
+	/* Request IRQ */
+	hw->irqnum = irq_of_parse_and_map(np, 0);
+	ret = request_irq(hw->irqnum, spi_ppc4xx_int,
+			  IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw);
+	if (ret) {
+		dev_err(dev, "unable to allocate interrupt\n");
+		goto free_gpios;
+	}
+
+	if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
+		dev_err(dev, "resource unavailable\n");
+		ret = -EBUSY;
+		goto request_mem_error;
+	}
+
+	hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
+
+	if (!hw->regs) {
+		dev_err(dev, "unable to memory map registers\n");
+		ret = -ENXIO;
+		goto map_io_error;
+	}
+
+	spi_ppc4xx_enable(hw);
+
+	/* Finally register our spi controller */
+	dev->dma_mask = 0;
+	ret = spi_bitbang_start(bbp);
+	if (ret) {
+		dev_err(dev, "failed to register SPI master\n");
+		goto unmap_regs;
+	}
+
+	dev_info(dev, "driver initialized\n");
+	of_register_spi_devices(master, np);
+
+	return 0;
+
+unmap_regs:
+	iounmap(hw->regs);
+map_io_error:
+	release_mem_region(hw->mapbase, hw->mapsize);
+request_mem_error:
+	free_irq(hw->irqnum, hw);
+free_gpios:
+	free_gpios(hw);
+free_master:
+	dev_set_drvdata(dev, NULL);
+	spi_master_put(master);
+
+	dev_err(dev, "initialization failed\n");
+	return ret;
+}
+
+static int __exit spi_ppc4xx_of_remove(struct of_device *op)
+{
+	struct spi_master *master = dev_get_drvdata(&op->dev);
+	struct ppc4xx_spi *hw = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&hw->bitbang);
+	dev_set_drvdata(&op->dev, NULL);
+	release_mem_region(hw->mapbase, hw->mapsize);
+	free_irq(hw->irqnum, hw);
+	iounmap(hw->regs);
+	free_gpios(hw);
+	return 0;
+}
+
+static struct of_device_id spi_ppc4xx_of_match[] = {
+	{ .compatible = "ibm,ppc4xx-spi", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
+
+static struct of_platform_driver spi_ppc4xx_of_driver = {
+	.match_table = spi_ppc4xx_of_match,
+	.probe = spi_ppc4xx_of_probe,
+	.remove = __exit_p(spi_ppc4xx_of_remove),
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init spi_ppc4xx_init(void)
+{
+	return of_register_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_init(spi_ppc4xx_init);
+
+static void __exit spi_ppc4xx_exit(void)
+{
+	of_unregister_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_exit(spi_ppc4xx_exit);
+
+MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
+MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
+MODULE_LICENSE("GPL");