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>

3 files changed, 433 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index bb233a9cbad2..8faa57a58dd1 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -231,6 +231,13 @@ config SPI_FSL_ESPI
           From MPC8536, 85xx platform uses the controller, and all P10xx,
           P20xx, P30xx,P40xx, P50xx uses this controller.
 
+config SPI_OC_TINY
+        tristate "OpenCores tiny SPI"
+        depends on GENERIC_GPIO
+        select SPI_BITBANG
+        help
+          This is the driver for OpenCores tiny SPI master controller.
+
 config SPI_OMAP_UWIRE
         tristate "OMAP1 MicroWire"
         depends on ARCH_OMAP1
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 86d1b5f9bbd9..c7e4c23c6f36 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_SPI_IMX)			+= spi_imx.o
 obj-$(CONFIG_SPI_LM70_LLP)              += spi_lm70llp.o
 obj-$(CONFIG_SPI_PXA2XX)                += pxa2xx_spi.o
 obj-$(CONFIG_SPI_PXA2XX_PCI)            += pxa2xx_spi_pci.o
+obj-$(CONFIG_SPI_OC_TINY)               += spi_oc_tiny.o
 obj-$(CONFIG_SPI_OMAP_UWIRE)            += omap_uwire.o
 obj-$(CONFIG_SPI_OMAP24XX)              += omap2_mcspi.o
 obj-$(CONFIG_SPI_OMAP_100K)             += omap_spi_100k.o
diff --git a/drivers/spi/spi_oc_tiny.c b/drivers/spi/spi_oc_tiny.c
new file mode 100644
index 000000000000..f1bde66cea19
--- /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);