spi: add OpenCores tiny SPI driver
This patch adds support of OpenCores tiny SPI driver.
http://opencores.org/project,tiny_spi
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/spi/spi_oc_tiny.c b/drivers/spi/spi_oc_tiny.c
new file mode 100644
index 0000000..f1bde66
--- /dev/null
+++ b/drivers/spi/spi_oc_tiny.c
@@ -0,0 +1,425 @@
+/*
+ * OpenCores tiny SPI master driver
+ *
+ * http://opencores.org/project,tiny_spi
+ *
+ * Copyright (C) 2011 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/spi/spi_oc_tiny.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+#include <linux/of.h>
+
+#define DRV_NAME "spi_oc_tiny"
+
+#define TINY_SPI_RXDATA 0
+#define TINY_SPI_TXDATA 4
+#define TINY_SPI_STATUS 8
+#define TINY_SPI_CONTROL 12
+#define TINY_SPI_BAUD 16
+
+#define TINY_SPI_STATUS_TXE 0x1
+#define TINY_SPI_STATUS_TXR 0x2
+
+struct tiny_spi {
+ /* bitbang has to be first */
+ struct spi_bitbang bitbang;
+ struct completion done;
+
+ void __iomem *base;
+ int irq;
+ unsigned int freq;
+ unsigned int baudwidth;
+ unsigned int baud;
+ unsigned int speed_hz;
+ unsigned int mode;
+ unsigned int len;
+ unsigned int txc, rxc;
+ const u8 *txp;
+ u8 *rxp;
+ unsigned int gpio_cs_count;
+ int *gpio_cs;
+};
+
+static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
+{
+ return spi_master_get_devdata(sdev->master);
+}
+
+static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
+{
+ struct tiny_spi *hw = tiny_spi_to_hw(spi);
+
+ return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
+}
+
+static void tiny_spi_chipselect(struct spi_device *spi, int is_active)
+{
+ struct tiny_spi *hw = tiny_spi_to_hw(spi);
+
+ if (hw->gpio_cs_count) {
+ gpio_set_value(hw->gpio_cs[spi->chip_select],
+ (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
+ }
+}
+
+static int tiny_spi_setup_transfer(struct spi_device *spi,
+ struct spi_transfer *t)
+{
+ struct tiny_spi *hw = tiny_spi_to_hw(spi);
+ unsigned int baud = hw->baud;
+
+ if (t) {
+ if (t->speed_hz && t->speed_hz != hw->speed_hz)
+ baud = tiny_spi_baud(spi, t->speed_hz);
+ }
+ writel(baud, hw->base + TINY_SPI_BAUD);
+ writel(hw->mode, hw->base + TINY_SPI_CONTROL);
+ return 0;
+}
+
+static int tiny_spi_setup(struct spi_device *spi)
+{
+ struct tiny_spi *hw = tiny_spi_to_hw(spi);
+
+ if (spi->max_speed_hz != hw->speed_hz) {
+ hw->speed_hz = spi->max_speed_hz;
+ hw->baud = tiny_spi_baud(spi, hw->speed_hz);
+ }
+ hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA);
+ return 0;
+}
+
+static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
+{
+ while (!(readb(hw->base + TINY_SPI_STATUS) &
+ TINY_SPI_STATUS_TXR))
+ cpu_relax();
+}
+
+static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
+{
+ while (!(readb(hw->base + TINY_SPI_STATUS) &
+ TINY_SPI_STATUS_TXE))
+ cpu_relax();
+}
+
+static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct tiny_spi *hw = tiny_spi_to_hw(spi);
+ const u8 *txp = t->tx_buf;
+ u8 *rxp = t->rx_buf;
+ unsigned int i;
+
+ if (hw->irq >= 0) {
+ /* use intrrupt driven data transfer */
+ hw->len = t->len;
+ hw->txp = t->tx_buf;
+ hw->rxp = t->rx_buf;
+ hw->txc = 0;
+ hw->rxc = 0;
+
+ /* send the first byte */
+ if (t->len > 1) {
+ writeb(hw->txp ? *hw->txp++ : 0,
+ hw->base + TINY_SPI_TXDATA);
+ hw->txc++;
+ writeb(hw->txp ? *hw->txp++ : 0,
+ hw->base + TINY_SPI_TXDATA);
+ hw->txc++;
+ writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
+ } else {
+ writeb(hw->txp ? *hw->txp++ : 0,
+ hw->base + TINY_SPI_TXDATA);
+ hw->txc++;
+ writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
+ }
+
+ wait_for_completion(&hw->done);
+ } else if (txp && rxp) {
+ /* we need to tighten the transfer loop */
+ writeb(*txp++, hw->base + TINY_SPI_TXDATA);
+ if (t->len > 1) {
+ writeb(*txp++, hw->base + TINY_SPI_TXDATA);
+ for (i = 2; i < t->len; i++) {
+ u8 rx, tx = *txp++;
+ tiny_spi_wait_txr(hw);
+ rx = readb(hw->base + TINY_SPI_TXDATA);
+ writeb(tx, hw->base + TINY_SPI_TXDATA);
+ *rxp++ = rx;
+ }
+ tiny_spi_wait_txr(hw);
+ *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
+ }
+ tiny_spi_wait_txe(hw);
+ *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
+ } else if (rxp) {
+ writeb(0, hw->base + TINY_SPI_TXDATA);
+ if (t->len > 1) {
+ writeb(0,
+ hw->base + TINY_SPI_TXDATA);
+ for (i = 2; i < t->len; i++) {
+ u8 rx;
+ tiny_spi_wait_txr(hw);
+ rx = readb(hw->base + TINY_SPI_TXDATA);
+ writeb(0, hw->base + TINY_SPI_TXDATA);
+ *rxp++ = rx;
+ }
+ tiny_spi_wait_txr(hw);
+ *rxp++ = readb(hw->base + TINY_SPI_TXDATA);
+ }
+ tiny_spi_wait_txe(hw);
+ *rxp++ = readb(hw->base + TINY_SPI_RXDATA);
+ } else if (txp) {
+ writeb(*txp++, hw->base + TINY_SPI_TXDATA);
+ if (t->len > 1) {
+ writeb(*txp++, hw->base + TINY_SPI_TXDATA);
+ for (i = 2; i < t->len; i++) {
+ u8 tx = *txp++;
+ tiny_spi_wait_txr(hw);
+ writeb(tx, hw->base + TINY_SPI_TXDATA);
+ }
+ }
+ tiny_spi_wait_txe(hw);
+ } else {
+ writeb(0, hw->base + TINY_SPI_TXDATA);
+ if (t->len > 1) {
+ writeb(0, hw->base + TINY_SPI_TXDATA);
+ for (i = 2; i < t->len; i++) {
+ tiny_spi_wait_txr(hw);
+ writeb(0, hw->base + TINY_SPI_TXDATA);
+ }
+ }
+ tiny_spi_wait_txe(hw);
+ }
+ return t->len;
+}
+
+static irqreturn_t tiny_spi_irq(int irq, void *dev)
+{
+ struct tiny_spi *hw = dev;
+
+ writeb(0, hw->base + TINY_SPI_STATUS);
+ if (hw->rxc + 1 == hw->len) {
+ if (hw->rxp)
+ *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
+ hw->rxc++;
+ complete(&hw->done);
+ } else {
+ if (hw->rxp)
+ *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
+ hw->rxc++;
+ if (hw->txc < hw->len) {
+ writeb(hw->txp ? *hw->txp++ : 0,
+ hw->base + TINY_SPI_TXDATA);
+ hw->txc++;
+ writeb(TINY_SPI_STATUS_TXR,
+ hw->base + TINY_SPI_STATUS);
+ } else {
+ writeb(TINY_SPI_STATUS_TXE,
+ hw->base + TINY_SPI_STATUS);
+ }
+ }
+ return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_OF
+#include <linux/of_gpio.h>
+
+static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
+{
+ struct tiny_spi *hw = platform_get_drvdata(pdev);
+ struct device_node *np = pdev->dev.of_node;
+ unsigned int i;
+ const __be32 *val;
+ int len;
+
+ if (!np)
+ return 0;
+ hw->gpio_cs_count = of_gpio_count(np);
+ if (hw->gpio_cs_count) {
+ hw->gpio_cs = devm_kzalloc(&pdev->dev,
+ hw->gpio_cs_count * sizeof(unsigned int),
+ GFP_KERNEL);
+ if (!hw->gpio_cs)
+ return -ENOMEM;
+ }
+ for (i = 0; i < hw->gpio_cs_count; i++) {
+ hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL);
+ if (hw->gpio_cs[i] < 0)
+ return -ENODEV;
+ }
+ hw->bitbang.master->dev.of_node = pdev->dev.of_node;
+ val = of_get_property(pdev->dev.of_node,
+ "clock-frequency", &len);
+ if (val && len >= sizeof(__be32))
+ hw->freq = be32_to_cpup(val);
+ val = of_get_property(pdev->dev.of_node, "baud-width", &len);
+ if (val && len >= sizeof(__be32))
+ hw->baudwidth = be32_to_cpup(val);
+ return 0;
+}
+#else /* !CONFIG_OF */
+static int __devinit tiny_spi_of_probe(struct platform_device *pdev)
+{
+ return 0;
+}
+#endif /* CONFIG_OF */
+
+static int __devinit tiny_spi_probe(struct platform_device *pdev)
+{
+ struct tiny_spi_platform_data *platp = pdev->dev.platform_data;
+ struct tiny_spi *hw;
+ struct spi_master *master;
+ struct resource *res;
+ unsigned int i;
+ int err = -ENODEV;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
+ if (!master)
+ return err;
+
+ /* setup the master state. */
+ master->bus_num = pdev->id;
+ master->num_chipselect = 255;
+ master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+ master->setup = tiny_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 = tiny_spi_setup_transfer;
+ hw->bitbang.chipselect = tiny_spi_chipselect;
+ hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
+
+ /* 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;
+ /* 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, tiny_spi_irq, 0,
+ pdev->name, hw);
+ if (err)
+ goto exit;
+ }
+ /* find platform data */
+ if (platp) {
+ hw->gpio_cs_count = platp->gpio_cs_count;
+ hw->gpio_cs = platp->gpio_cs;
+ if (platp->gpio_cs_count && !platp->gpio_cs)
+ goto exit_busy;
+ hw->freq = platp->freq;
+ hw->baudwidth = platp->baudwidth;
+ } else {
+ err = tiny_spi_of_probe(pdev);
+ if (err)
+ goto exit;
+ }
+ for (i = 0; i < hw->gpio_cs_count; i++) {
+ err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev));
+ if (err)
+ goto exit_gpio;
+ gpio_direction_output(hw->gpio_cs[i], 1);
+ }
+ hw->bitbang.master->num_chipselect = max(1U, hw->gpio_cs_count);
+
+ /* 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_gpio:
+ while (i-- > 0)
+ gpio_free(hw->gpio_cs[i]);
+exit_busy:
+ err = -EBUSY;
+exit:
+ platform_set_drvdata(pdev, NULL);
+ spi_master_put(master);
+ return err;
+}
+
+static int __devexit tiny_spi_remove(struct platform_device *pdev)
+{
+ struct tiny_spi *hw = platform_get_drvdata(pdev);
+ struct spi_master *master = hw->bitbang.master;
+ unsigned int i;
+
+ spi_bitbang_stop(&hw->bitbang);
+ for (i = 0; i < hw->gpio_cs_count; i++)
+ gpio_free(hw->gpio_cs[i]);
+ platform_set_drvdata(pdev, NULL);
+ spi_master_put(master);
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id tiny_spi_match[] = {
+ { .compatible = "opencores,tiny-spi-rtlsvn2", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, tiny_spi_match);
+#else /* CONFIG_OF */
+#define tiny_spi_match NULL
+#endif /* CONFIG_OF */
+
+static struct platform_driver tiny_spi_driver = {
+ .probe = tiny_spi_probe,
+ .remove = __devexit_p(tiny_spi_remove),
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .pm = NULL,
+ .of_match_table = tiny_spi_match,
+ },
+};
+
+static int __init tiny_spi_init(void)
+{
+ return platform_driver_register(&tiny_spi_driver);
+}
+module_init(tiny_spi_init);
+
+static void __exit tiny_spi_exit(void)
+{
+ platform_driver_unregister(&tiny_spi_driver);
+}
+module_exit(tiny_spi_exit);
+
+MODULE_DESCRIPTION("OpenCores tiny SPI driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);