spi: New driver for Altera SPI

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>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/spi/spi_altera.txt

+Altera SPI
+
+Required properties:
+- compatible : should be "ALTR,spi-1.0".

drivers/spi/Kconfig

@@ -53,6 +53,12 @@ if SPI_MASTER
 
 comment "SPI Master Controller Drivers"
 
+config SPI_ALTERA
+	tristate "Altera SPI Controller"
+	select SPI_BITBANG
+	help
+	  This is the driver for the Altera SPI Controller.
+
 config SPI_ATH79
 	tristate "Atheros AR71XX/AR724X/AR913X SPI controller driver"
 	depends on ATH79 && GENERIC_GPIO

drivers/spi/Makefile

@@ -9,6 +9,7 @@ ccflags-$(CONFIG_SPI_DEBUG) := -DDEBUG
 obj-$(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-$(CONFIG_SPI_ATH79)			+= ath79_spi.o
 obj-$(CONFIG_SPI_BFIN)			+= spi_bfin5xx.o

drivers/spi/spi_altera.c

+/*
+ * 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/interrupt.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/io.h>
+#include <linux/of.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;
+
+	void __iomem *base;
+	int irq;
+	int len;
+	int count;
+	int bytes_per_word;
+	unsigned long imr;
+
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+};
+
+static inline struct altera_spi *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 = altera_spi_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)
+{
+	return 0;
+}
+
+static int altera_spi_setup(struct spi_device *spi)
+{
+	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 = altera_spi_to_hw(spi);
+
+	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;
+
+	if (hw->irq >= 0) {
+		/* enable receive interrupt */
+		hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
+		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+
+		/* send the first byte */
+		writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
+
+		wait_for_completion(&hw->done);
+		/* disable receive interrupt */
+		hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
+		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+	} else {
+		/* send the first byte */
+		writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
+
+		while (1) {
+			unsigned int rxd;
+
+			while (!(readl(hw->base + ALTERA_SPI_STATUS) &
+				 ALTERA_SPI_STATUS_RRDY_MSK))
+				cpu_relax();
+
+			rxd = readl(hw->base + ALTERA_SPI_RXDATA);
+			if (hw->rx) {
+				switch (hw->bytes_per_word) {
+				case 1:
+					hw->rx[hw->count] = rxd;
+					break;
+				case 2:
+					hw->rx[hw->count * 2] = rxd;
+					hw->rx[hw->count * 2 + 1] = rxd >> 8;
+					break;
+				}
+			}
+
+			hw->count++;
+
+			if (hw->count < hw->len)
+				writel(hw_txbyte(hw, hw->count),
+				       hw->base + ALTERA_SPI_TXDATA);
+			else
+				break;
+		}
+
+	}
+
+	return hw->count * hw->bytes_per_word;
+}
+
+static irqreturn_t altera_spi_irq(int irq, void *dev)
+{
+	struct altera_spi *hw = dev;
+	unsigned int rxd;
+
+	rxd = readl(hw->base + ALTERA_SPI_RXDATA);
+	if (hw->rx) {
+		switch (hw->bytes_per_word) {
+		case 1:
+			hw->rx[hw->count] = rxd;
+			break;
+		case 2:
+			hw->rx[hw->count * 2] = rxd;
+			hw->rx[hw->count * 2 + 1] = rxd >> 8;
+			break;
+		}
+	}
+
+	hw->count++;
+
+	if (hw->count < hw->len)
+		writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
+	else
+		complete(&hw->done);
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit altera_spi_probe(struct platform_device *pdev)
+{
+	struct altera_spi_platform_data *platp = pdev->dev.platform_data;
+	struct altera_spi *hw;
+	struct spi_master *master;
+	struct resource *res;
+	int err = -ENODEV;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
+	if (!master)
+		return err;
+
+	/* setup the master state. */
+	master->bus_num = pdev->id;
+	master->num_chipselect = 16;
+	master->mode_bits = SPI_CS_HIGH;
+	master->setup = altera_spi_setup;
+
+	hw = spi_master_get_devdata(master);
+	platform_set_drvdata(pdev, hw);
+
+	/* setup the state for the bitbang driver */
+	hw->bitbang.master = spi_master_get(master);
+	if (!hw->bitbang.master)
+		return err;
+	hw->bitbang.setup_transfer = altera_spi_setupxfer;
+	hw->bitbang.chipselect = altera_spi_chipsel;
+	hw->bitbang.txrx_bufs = altera_spi_txrx;
+
+	/* find and map our resources */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto exit_busy;
+	if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
+				     pdev->name))
+		goto exit_busy;
+	hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
+					resource_size(res));
+	if (!hw->base)
+		goto exit_busy;
+	/* 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 */
+	/* irq is optional */
+	hw->irq = platform_get_irq(pdev, 0);
+	if (hw->irq >= 0) {
+		init_completion(&hw->done);
+		err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
+				       pdev->name, hw);
+		if (err)
+			goto exit;
+	}
+	/* find platform data */
+	if (!platp)
+		hw->bitbang.master->dev.of_node = pdev->dev.of_node;
+
+	/* register our spi controller */
+	err = spi_bitbang_start(&hw->bitbang);
+	if (err)
+		goto exit;
+	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
+
+	return 0;
+
+exit_busy:
+	err = -EBUSY;
+exit:
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(master);
+	return err;
+}
+
+static int __devexit altera_spi_remove(struct platform_device *dev)
+{
+	struct altera_spi *hw = platform_get_drvdata(dev);
+	struct spi_master *master = hw->bitbang.master;
+
+	spi_bitbang_stop(&hw->bitbang);
+	platform_set_drvdata(dev, NULL);
+	spi_master_put(master);
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id altera_spi_match[] = {
+	{ .compatible = "ALTR,spi-1.0", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, altera_spi_match);
+#else /* CONFIG_OF */
+#define altera_spi_match NULL
+#endif /* CONFIG_OF */
+
+static struct platform_driver altera_spi_driver = {
+	.probe = altera_spi_probe,
+	.remove = __devexit_p(altera_spi_remove),
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.pm = NULL,
+		.of_match_table = altera_spi_match,
+	},
+};
+
+static int __init altera_spi_init(void)
+{
+	return platform_driver_register(&altera_spi_driver);
+}
+module_init(altera_spi_init);
+
+static void __exit altera_spi_exit(void)
+{
+	platform_driver_unregister(&altera_spi_driver);
+}
+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);