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Subject[PATCH] spi: New driver for Altera SPI
Date
This patch adds a new SPI driver to support the Altera SOPC Builder
SPI component. It uses the bitbanging library.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
---
drivers/spi/Kconfig | 7 +
drivers/spi/Makefile | 1 +
drivers/spi/spi_altera.c | 397 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 405 insertions(+), 0 deletions(-)
create mode 100644 drivers/spi/spi_altera.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 4b6f7cb..64f1148 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -53,6 +53,13 @@ if SPI_MASTER

comment "SPI Master Controller Drivers"

+config SPI_ALTERA
+ tristate "Altera SPI Controller"
+ depends on EMBEDDED
+ select SPI_BITBANG
+ help
+ This is the driver for the Altera SPI Controller.
+
config SPI_ATMEL
tristate "Atmel SPI Controller"
depends on (ARCH_AT91 || AVR32)
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 21a1182..f5f43f1 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -11,6 +11,7 @@ endif
obj-$(CONFIG_SPI_MASTER) += spi.o

# SPI master controller drivers (bus)
+obj-$(CONFIG_SPI_ALTERA) += spi_altera.o
obj-$(CONFIG_SPI_ATMEL) += atmel_spi.o
obj-$(CONFIG_SPI_BFIN) += spi_bfin5xx.o
obj-$(CONFIG_SPI_BITBANG) += spi_bitbang.o
diff --git a/drivers/spi/spi_altera.c b/drivers/spi/spi_altera.c
new file mode 100644
index 0000000..337dc95
--- /dev/null
+++ b/drivers/spi/spi_altera.c
@@ -0,0 +1,397 @@
+/*
+ * Altera SPI driver
+ *
+ * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * Based on spi_s3c24xx.c, which is:
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/io.h>
+
+#define DRV_NAME "spi_altera"
+
+#define ALTERA_SPI_RXDATA 0
+#define ALTERA_SPI_TXDATA 4
+#define ALTERA_SPI_STATUS 8
+#define ALTERA_SPI_CONTROL 12
+#define ALTERA_SPI_SLAVE_SEL 20
+
+#define ALTERA_SPI_STATUS_ROE_MSK (0x8)
+#define ALTERA_SPI_STATUS_TOE_MSK (0x10)
+#define ALTERA_SPI_STATUS_TMT_MSK (0x20)
+#define ALTERA_SPI_STATUS_TRDY_MSK (0x40)
+#define ALTERA_SPI_STATUS_RRDY_MSK (0x80)
+#define ALTERA_SPI_STATUS_E_MSK (0x100)
+
+#define ALTERA_SPI_CONTROL_IROE_MSK (0x8)
+#define ALTERA_SPI_CONTROL_ITOE_MSK (0x10)
+#define ALTERA_SPI_CONTROL_ITRDY_MSK (0x40)
+#define ALTERA_SPI_CONTROL_IRRDY_MSK (0x80)
+#define ALTERA_SPI_CONTROL_IE_MSK (0x100)
+#define ALTERA_SPI_CONTROL_SSO_MSK (0x400)
+
+struct altera_spi {
+ /* bitbang has to be first */
+ struct spi_bitbang bitbang;
+ struct completion done;
+
+ unsigned long base;
+ int irq;
+ int len;
+ int count;
+ int bytes_per_word;
+ unsigned long imr;
+
+ /* data buffers */
+ const unsigned char *tx;
+ unsigned char *rx;
+
+ struct resource *ioarea;
+ struct spi_master *master;
+ struct spi_device *curdev;
+ struct device *dev;
+};
+
+static inline struct altera_spi *to_hw(struct spi_device *sdev)
+{
+ return spi_master_get_devdata(sdev->master);
+}
+
+static void altera_spi_chipsel(struct spi_device *spi, int value)
+{
+ struct altera_spi *hw = to_hw(spi);
+
+ if (spi->mode & SPI_CS_HIGH) {
+ switch (value) {
+ case BITBANG_CS_INACTIVE:
+ writel(1 << spi->chip_select,
+ hw->base + ALTERA_SPI_SLAVE_SEL);
+ hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+ break;
+
+ case BITBANG_CS_ACTIVE:
+ hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+ writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
+ break;
+ }
+ } else {
+ switch (value) {
+ case BITBANG_CS_INACTIVE:
+ hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+ break;
+
+ case BITBANG_CS_ACTIVE:
+ writel(1 << spi->chip_select,
+ hw->base + ALTERA_SPI_SLAVE_SEL);
+ hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+ break;
+ }
+ }
+}
+
+static int altera_spi_setupxfer(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct altera_spi *hw = to_hw(spi);
+
+ spin_lock(&hw->bitbang.lock);
+ if (!hw->bitbang.busy) {
+ hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+ /* need to ndelay for 0.5 clocktick ? */
+ }
+ spin_unlock(&hw->bitbang.lock);
+
+ return 0;
+}
+
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
+
+static int altera_spi_setup(struct spi_device *spi)
+{
+ int ret;
+
+ if (!spi->bits_per_word)
+ spi->bits_per_word = 8;
+
+ if (spi->mode & ~MODEBITS) {
+ dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+ spi->mode & ~MODEBITS);
+ return -EINVAL;
+ }
+
+ ret = altera_spi_setupxfer(spi, NULL);
+ if (ret < 0) {
+ dev_err(&spi->dev, "setupxfer returned %d\n", ret);
+ return ret;
+ }
+
+ 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 inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
+{
+ if (hw->tx) {
+ switch (hw->bytes_per_word) {
+ case 1:
+ return hw->tx[count];
+ case 2:
+ return (hw->tx[count * 2]
+ | (hw->tx[count * 2 + 1] << 8));
+ }
+ }
+
+ return 0;
+}
+
+static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct altera_spi *hw = to_hw(spi);
+
+ dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+ t->tx_buf, t->rx_buf, t->len);
+
+ hw->tx = t->tx_buf;
+ hw->rx = t->rx_buf;
+ hw->count = 0;
+ hw->bytes_per_word = (t->bits_per_word ? : spi->bits_per_word) / 8;
+ hw->len = t->len / hw->bytes_per_word;
+
+ init_completion(&hw->done);
+
+ /* send the first byte */
+ writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
+
+ wait_for_completion(&hw->done);
+
+ return hw->count * hw->bytes_per_word;
+}
+
+static irqreturn_t altera_spi_irq(int irq, void *dev)
+{
+ struct altera_spi *hw = dev;
+ unsigned int spsta = readl(hw->base + ALTERA_SPI_STATUS);
+ unsigned int count = hw->count;
+ unsigned int rxd;
+
+ if (spsta & ALTERA_SPI_STATUS_ROE_MSK) {
+ dev_dbg(hw->dev, "data-collision\n");
+ complete(&hw->done);
+ goto irq_done;
+ }
+
+ if (!(spsta & ALTERA_SPI_STATUS_TRDY_MSK)) {
+ dev_dbg(hw->dev, "spi not ready for tx?\n");
+ complete(&hw->done);
+ goto irq_done;
+ }
+
+ hw->count++;
+
+ rxd = readl(hw->base + ALTERA_SPI_RXDATA);
+ if (hw->rx) {
+ switch (hw->bytes_per_word) {
+ case 1:
+ hw->rx[count] = rxd;
+ break;
+ case 2:
+ hw->rx[count * 2] = rxd;
+ hw->rx[count * 2 + 1] = rxd >> 8;
+ break;
+ }
+ }
+
+ count++;
+
+ if (count < hw->len)
+ writel(hw_txbyte(hw, count), hw->base + ALTERA_SPI_TXDATA);
+ else
+ complete(&hw->done);
+
+irq_done:
+ return IRQ_HANDLED;
+}
+
+static int __init altera_spi_probe(struct platform_device *pdev)
+{
+ struct altera_spi *hw;
+ struct spi_master *master;
+ struct resource *res;
+ int err = 0;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
+ if (master == NULL) {
+ dev_err(&pdev->dev, "No memory for spi_master\n");
+ err = -ENOMEM;
+ goto err_nomem;
+ }
+
+ hw = spi_master_get_devdata(master);
+ memset(hw, 0, sizeof(struct altera_spi));
+
+ hw->master = spi_master_get(master);
+ hw->dev = &pdev->dev;
+
+ platform_set_drvdata(pdev, hw);
+ init_completion(&hw->done);
+
+ /* setup the master state. */
+
+ master->bus_num = pdev->id;
+ master->num_chipselect = 16;
+
+ /* setup the state for the bitbang driver */
+
+ hw->bitbang.master = hw->master;
+ hw->bitbang.setup_transfer = altera_spi_setupxfer;
+ hw->bitbang.chipselect = altera_spi_chipsel;
+ hw->bitbang.txrx_bufs = altera_spi_txrx;
+ hw->bitbang.master->setup = altera_spi_setup;
+
+ dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);
+
+ /* find and map our resources */
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res == NULL) {
+ dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
+ err = -ENOENT;
+ goto err_no_iores;
+ }
+
+ hw->ioarea = request_mem_region(res->start, (res->end - res->start) + 1,
+ pdev->name);
+
+ if (hw->ioarea == NULL) {
+ dev_err(&pdev->dev, "Cannot reserve region\n");
+ err = -ENXIO;
+ goto err_no_iores;
+ }
+
+ hw->base =
+ (unsigned long)ioremap(res->start, (res->end - res->start) + 1);
+ if (hw->base == 0) {
+ dev_err(&pdev->dev, "Cannot map IO\n");
+ err = -ENXIO;
+ goto err_no_iomap;
+ }
+
+ hw->irq = platform_get_irq(pdev, 0);
+ if (hw->irq < 0) {
+ dev_err(&pdev->dev, "No IRQ specified\n");
+ err = -ENOENT;
+ goto err_no_irq;
+ }
+
+ /* program defaults into the registers */
+ hw->imr = 0; /* disable spi interrupts */
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+ writel(0, hw->base + ALTERA_SPI_STATUS); /* clear status reg */
+ if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
+ readl(hw->base + ALTERA_SPI_RXDATA); /* flush rxdata */
+
+ err = request_irq(hw->irq, altera_spi_irq, 0, pdev->name, hw);
+ if (err) {
+ dev_err(&pdev->dev, "Cannot claim IRQ\n");
+ goto err_no_irq;
+ }
+
+ /* enable receive interrupt */
+ hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+
+ /* register our spi controller */
+
+ err = spi_bitbang_start(&hw->bitbang);
+ if (err) {
+ dev_err(&pdev->dev, "Failed to register SPI master\n");
+ goto err_register;
+ }
+
+ return 0;
+
+err_register:
+ free_irq(hw->irq, hw);
+err_no_irq:
+ iounmap((void *)hw->base);
+err_no_iomap:
+ release_resource(hw->ioarea);
+ kfree(hw->ioarea);
+err_no_iores:
+ spi_master_put(hw->master);;
+err_nomem:
+ return err;
+}
+
+static int __exit altera_spi_remove(struct platform_device *dev)
+{
+ struct altera_spi *hw = platform_get_drvdata(dev);
+
+ /* disable spi interrupts */
+ hw->imr = 0;
+ writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+
+ platform_set_drvdata(dev, NULL);
+
+ spi_unregister_master(hw->master);
+
+ free_irq(hw->irq, hw);
+ iounmap((void *)hw->base);
+
+ release_resource(hw->ioarea);
+ kfree(hw->ioarea);
+
+ spi_master_put(hw->master);
+ return 0;
+}
+
+static struct platform_driver altera_spidrv = {
+ .remove = __exit_p(altera_spi_remove),
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .pm = NULL,
+ },
+};
+
+static int __init altera_spi_init(void)
+{
+ return platform_driver_probe(&altera_spidrv, altera_spi_probe);
+}
+
+static void __exit altera_spi_exit(void)
+{
+ platform_driver_unregister(&altera_spidrv);
+}
+
+module_init(altera_spi_init);
+module_exit(altera_spi_exit);
+
+MODULE_DESCRIPTION("Altera SPI driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
--
1.6.2.5


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