SPI master driver for Xilinx virtex

Simple SPI master driver for Xilinx SPI controller.
No support for multiple masters.
Not using level 1 drivers from EDK.

[akpm@linux-foundation.org: uninlining]
Signed-off-by: Yuri Frolov <yfrolov@ru.mvista.com>
Signed-off-by: Andrei Konovalov <akonovalov@ru.mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 434 insertions, 0 deletions

diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c
new file mode 100644
index 00000000000..f0bf9a68e96
--- /dev/null
+++ b/drivers/spi/xilinx_spi.c
@@ -0,0 +1,434 @@
+/*
+ * xilinx_spi.c
+ *
+ * Xilinx SPI controller driver (master mode only)
+ *
+ * Author: MontaVista Software, Inc.
+ *	source@mvista.com
+ *
+ * 2002-2007 (c) MontaVista Software, Inc.  This file is licensed under the
+ * terms of the GNU General Public License version 2.  This program is licensed
+ * "as is" without any warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/io.h>
+
+#include <syslib/virtex_devices.h>
+
+#define XILINX_SPI_NAME "xspi"
+
+/* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
+ * Product Specification", DS464
+ */
+#define XSPI_CR_OFFSET		0x62	/* 16-bit Control Register */
+
+#define XSPI_CR_ENABLE		0x02
+#define XSPI_CR_MASTER_MODE	0x04
+#define XSPI_CR_CPOL		0x08
+#define XSPI_CR_CPHA		0x10
+#define XSPI_CR_MODE_MASK	(XSPI_CR_CPHA | XSPI_CR_CPOL)
+#define XSPI_CR_TXFIFO_RESET	0x20
+#define XSPI_CR_RXFIFO_RESET	0x40
+#define XSPI_CR_MANUAL_SSELECT	0x80
+#define XSPI_CR_TRANS_INHIBIT	0x100
+
+#define XSPI_SR_OFFSET		0x67	/* 8-bit Status Register */
+
+#define XSPI_SR_RX_EMPTY_MASK	0x01	/* Receive FIFO is empty */
+#define XSPI_SR_RX_FULL_MASK	0x02	/* Receive FIFO is full */
+#define XSPI_SR_TX_EMPTY_MASK	0x04	/* Transmit FIFO is empty */
+#define XSPI_SR_TX_FULL_MASK	0x08	/* Transmit FIFO is full */
+#define XSPI_SR_MODE_FAULT_MASK	0x10	/* Mode fault error */
+
+#define XSPI_TXD_OFFSET		0x6b	/* 8-bit Data Transmit Register */
+#define XSPI_RXD_OFFSET		0x6f	/* 8-bit Data Receive Register */
+
+#define XSPI_SSR_OFFSET		0x70	/* 32-bit Slave Select Register */
+
+/* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
+ * IPIF registers are 32 bit
+ */
+#define XIPIF_V123B_DGIER_OFFSET	0x1c	/* IPIF global int enable reg */
+#define XIPIF_V123B_GINTR_ENABLE	0x80000000
+
+#define XIPIF_V123B_IISR_OFFSET		0x20	/* IPIF interrupt status reg */
+#define XIPIF_V123B_IIER_OFFSET		0x28	/* IPIF interrupt enable reg */
+
+#define XSPI_INTR_MODE_FAULT		0x01	/* Mode fault error */
+#define XSPI_INTR_SLAVE_MODE_FAULT	0x02	/* Selected as slave while
+						 * disabled */
+#define XSPI_INTR_TX_EMPTY		0x04	/* TxFIFO is empty */
+#define XSPI_INTR_TX_UNDERRUN		0x08	/* TxFIFO was underrun */
+#define XSPI_INTR_RX_FULL		0x10	/* RxFIFO is full */
+#define XSPI_INTR_RX_OVERRUN		0x20	/* RxFIFO was overrun */
+
+#define XIPIF_V123B_RESETR_OFFSET	0x40	/* IPIF reset register */
+#define XIPIF_V123B_RESET_MASK		0x0a	/* the value to write */
+
+struct xilinx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	void __iomem	*regs;	/* virt. address of the control registers */
+
+	u32		irq;
+
+	u32		speed_hz; /* SCK has a fixed frequency of speed_hz Hz */
+
+	u8 *rx_ptr;		/* pointer in the Tx buffer */
+	const u8 *tx_ptr;	/* pointer in the Rx buffer */
+	int remaining_bytes;	/* the number of bytes left to transfer */
+};
+
+static void xspi_init_hw(void __iomem *regs_base)
+{
+	/* Reset the SPI device */
+	out_be32(regs_base + XIPIF_V123B_RESETR_OFFSET,
+		 XIPIF_V123B_RESET_MASK);
+	/* Disable all the interrupts just in case */
+	out_be32(regs_base + XIPIF_V123B_IIER_OFFSET, 0);
+	/* Enable the global IPIF interrupt */
+	out_be32(regs_base + XIPIF_V123B_DGIER_OFFSET,
+		 XIPIF_V123B_GINTR_ENABLE);
+	/* Deselect the slave on the SPI bus */
+	out_be32(regs_base + XSPI_SSR_OFFSET, 0xffff);
+	/* Disable the transmitter, enable Manual Slave Select Assertion,
+	 * put SPI controller into master mode, and enable it */
+	out_be16(regs_base + XSPI_CR_OFFSET,
+		 XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT
+		 | XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE);
+}
+
+static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
+{
+	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
+
+	if (is_on == BITBANG_CS_INACTIVE) {
+		/* Deselect the slave on the SPI bus */
+		out_be32(xspi->regs + XSPI_SSR_OFFSET, 0xffff);
+	} else if (is_on == BITBANG_CS_ACTIVE) {
+		/* Set the SPI clock phase and polarity */
+		u16 cr = in_be16(xspi->regs + XSPI_CR_OFFSET)
+			 & ~XSPI_CR_MODE_MASK;
+		if (spi->mode & SPI_CPHA)
+			cr |= XSPI_CR_CPHA;
+		if (spi->mode & SPI_CPOL)
+			cr |= XSPI_CR_CPOL;
+		out_be16(xspi->regs + XSPI_CR_OFFSET, cr);
+
+		/* We do not check spi->max_speed_hz here as the SPI clock
+		 * frequency is not software programmable (the IP block design
+		 * parameter)
+		 */
+
+		/* Activate the chip select */
+		out_be32(xspi->regs + XSPI_SSR_OFFSET,
+			 ~(0x0001 << spi->chip_select));
+	}
+}
+
+/* spi_bitbang requires custom setup_transfer() to be defined if there is a
+ * custom txrx_bufs(). We have nothing to setup here as the SPI IP block
+ * supports just 8 bits per word, and SPI clock can't be changed in software.
+ * Check for 8 bits per word. Chip select delay calculations could be
+ * added here as soon as bitbang_work() can be made aware of the delay value.
+ */
+static int xilinx_spi_setup_transfer(struct spi_device *spi,
+		struct spi_transfer *t)
+{
+	u8 bits_per_word;
+	u32 hz;
+	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
+
+	bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word;
+	hz = (t) ? t->speed_hz : spi->max_speed_hz;
+	if (bits_per_word != 8) {
+		dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
+			__FUNCTION__, bits_per_word);
+		return -EINVAL;
+	}
+
+	if (hz && xspi->speed_hz > hz) {
+		dev_err(&spi->dev, "%s, unsupported clock rate %uHz\n",
+			__FUNCTION__, hz);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA)
+
+static int xilinx_spi_setup(struct spi_device *spi)
+{
+	struct spi_bitbang *bitbang;
+	struct xilinx_spi *xspi;
+	int retval;
+
+	xspi = spi_master_get_devdata(spi->master);
+	bitbang = &xspi->bitbang;
+
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	if (spi->mode & ~MODEBITS) {
+		dev_err(&spi->dev, "%s, unsupported mode bits %x\n",
+			__FUNCTION__, spi->mode & ~MODEBITS);
+		return -EINVAL;
+	}
+
+	retval = xilinx_spi_setup_transfer(spi, NULL);
+	if (retval < 0)
+		return retval;
+
+	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
+		__FUNCTION__, spi->mode & MODEBITS, spi->bits_per_word, 0);
+
+	return 0;
+}
+
+static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi)
+{
+	u8 sr;
+
+	/* Fill the Tx FIFO with as many bytes as possible */
+	sr = in_8(xspi->regs + XSPI_SR_OFFSET);
+	while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) {
+		if (xspi->tx_ptr) {
+			out_8(xspi->regs + XSPI_TXD_OFFSET, *xspi->tx_ptr++);
+		} else {
+			out_8(xspi->regs + XSPI_TXD_OFFSET, 0);
+		}
+		xspi->remaining_bytes--;
+		sr = in_8(xspi->regs + XSPI_SR_OFFSET);
+	}
+}
+
+static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
+	u32 ipif_ier;
+	u16 cr;
+
+	/* We get here with transmitter inhibited */
+
+	xspi->tx_ptr = t->tx_buf;
+	xspi->rx_ptr = t->rx_buf;
+	xspi->remaining_bytes = t->len;
+	INIT_COMPLETION(xspi->done);
+
+	xilinx_spi_fill_tx_fifo(xspi);
+
+	/* Enable the transmit empty interrupt, which we use to determine
+	 * progress on the transmission.
+	 */
+	ipif_ier = in_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET);
+	out_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET,
+		 ipif_ier | XSPI_INTR_TX_EMPTY);
+
+	/* Start the transfer by not inhibiting the transmitter any longer */
+	cr = in_be16(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_TRANS_INHIBIT;
+	out_be16(xspi->regs + XSPI_CR_OFFSET, cr);
+
+	wait_for_completion(&xspi->done);
+
+	/* Disable the transmit empty interrupt */
+	out_be32(xspi->regs + XIPIF_V123B_IIER_OFFSET, ipif_ier);
+
+	return t->len - xspi->remaining_bytes;
+}
+
+
+/* This driver supports single master mode only. Hence Tx FIFO Empty
+ * is the only interrupt we care about.
+ * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
+ * Fault are not to happen.
+ */
+static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
+{
+	struct xilinx_spi *xspi = dev_id;
+	u32 ipif_isr;
+
+	/* Get the IPIF interrupts, and clear them immediately */
+	ipif_isr = in_be32(xspi->regs + XIPIF_V123B_IISR_OFFSET);
+	out_be32(xspi->regs + XIPIF_V123B_IISR_OFFSET, ipif_isr);
+
+	if (ipif_isr & XSPI_INTR_TX_EMPTY) {	/* Transmission completed */
+		u16 cr;
+		u8 sr;
+
+		/* A transmit has just completed. Process received data and
+		 * check for more data to transmit. Always inhibit the
+		 * transmitter while the Isr refills the transmit register/FIFO,
+		 * or make sure it is stopped if we're done.
+		 */
+		cr = in_be16(xspi->regs + XSPI_CR_OFFSET);
+		out_be16(xspi->regs + XSPI_CR_OFFSET,
+			 cr | XSPI_CR_TRANS_INHIBIT);
+
+		/* Read out all the data from the Rx FIFO */
+		sr = in_8(xspi->regs + XSPI_SR_OFFSET);
+		while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
+			u8 data;
+
+			data = in_8(xspi->regs + XSPI_RXD_OFFSET);
+			if (xspi->rx_ptr) {
+				*xspi->rx_ptr++ = data;
+			}
+			sr = in_8(xspi->regs + XSPI_SR_OFFSET);
+		}
+
+		/* See if there is more data to send */
+		if (xspi->remaining_bytes > 0) {
+			xilinx_spi_fill_tx_fifo(xspi);
+			/* Start the transfer by not inhibiting the
+			 * transmitter any longer
+			 */
+			out_be16(xspi->regs + XSPI_CR_OFFSET, cr);
+		} else {
+			/* No more data to send.
+			 * Indicate the transfer is completed.
+			 */
+			complete(&xspi->done);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int __init xilinx_spi_probe(struct platform_device *dev)
+{
+	int ret = 0;
+	struct spi_master *master;
+	struct xilinx_spi *xspi;
+	struct xspi_platform_data *pdata;
+	struct resource *r;
+
+	/* Get resources(memory, IRQ) associated with the device */
+	master = spi_alloc_master(&dev->dev, sizeof(struct xilinx_spi));
+
+	if (master == NULL) {
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(dev, master);
+	pdata = dev->dev.platform_data;
+
+	if (pdata == NULL) {
+		ret = -ENODEV;
+		goto put_master;
+	}
+
+	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		ret = -ENODEV;
+		goto put_master;
+	}
+
+	xspi = spi_master_get_devdata(master);
+	xspi->bitbang.master = spi_master_get(master);
+	xspi->bitbang.chipselect = xilinx_spi_chipselect;
+	xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
+	xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
+	xspi->bitbang.master->setup = xilinx_spi_setup;
+	init_completion(&xspi->done);
+
+	if (!request_mem_region(r->start,
+			r->end - r->start + 1, XILINX_SPI_NAME)) {
+		ret = -ENXIO;
+		goto put_master;
+	}
+
+	xspi->regs = ioremap(r->start, r->end - r->start + 1);
+	if (xspi->regs == NULL) {
+		ret = -ENOMEM;
+		goto put_master;
+	}
+
+	xspi->irq = platform_get_irq(dev, 0);
+	if (xspi->irq < 0) {
+		ret = -ENXIO;
+		goto unmap_io;
+	}
+
+	master->bus_num = pdata->bus_num;
+	master->num_chipselect = pdata->num_chipselect;
+	xspi->speed_hz = pdata->speed_hz;
+
+	/* SPI controller initializations */
+	xspi_init_hw(xspi->regs);
+
+	/* Register for SPI Interrupt */
+	ret = request_irq(xspi->irq, xilinx_spi_irq, 0, XILINX_SPI_NAME, xspi);
+	if (ret != 0)
+		goto unmap_io;
+
+	ret = spi_bitbang_start(&xspi->bitbang);
+	if (ret != 0) {
+		dev_err(&dev->dev, "spi_bitbang_start FAILED\n");
+		goto free_irq;
+	}
+
+	dev_info(&dev->dev, "at 0x%08X mapped to 0x%08X, irq=%d\n",
+			r->start, (u32)xspi->regs, xspi->irq);
+
+	return ret;
+
+free_irq:
+	free_irq(xspi->irq, xspi);
+unmap_io:
+	iounmap(xspi->regs);
+put_master:
+	spi_master_put(master);
+	return ret;
+}
+
+static int __devexit xilinx_spi_remove(struct platform_device *dev)
+{
+	struct xilinx_spi *xspi;
+	struct spi_master *master;
+
+	master = platform_get_drvdata(dev);
+	xspi = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&xspi->bitbang);
+	free_irq(xspi->irq, xspi);
+	iounmap(xspi->regs);
+	platform_set_drvdata(dev, 0);
+	spi_master_put(xspi->bitbang.master);
+
+	return 0;
+}
+
+static struct platform_driver xilinx_spi_driver = {
+	.probe	= xilinx_spi_probe,
+	.remove	= __devexit_p(xilinx_spi_remove),
+	.driver = {
+		.name = XILINX_SPI_NAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init xilinx_spi_init(void)
+{
+	return platform_driver_register(&xilinx_spi_driver);
+}
+module_init(xilinx_spi_init);
+
+static void __exit xilinx_spi_exit(void)
+{
+	platform_driver_unregister(&xilinx_spi_driver);
+}
+module_exit(xilinx_spi_exit);
+
+MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
+MODULE_DESCRIPTION("Xilinx SPI driver");
+MODULE_LICENSE("GPL");