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/Documentation/devicetree/bindings/spi/spi_oc_tiny.txt b/Documentation/devicetree/bindings/spi/spi_oc_tiny.txt
new file mode 100644 (file)
index 0000000..d95c0b3
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi_oc_tiny.txt
@@ -0,0 +1,12 @@
+OpenCores tiny SPI
+
+Required properties:
+- compatible : should be "opencores,tiny-spi-rtlsvn2".
+- gpios : should specify GPIOs used for chipselect.
+Optional properties:
+- clock-frequency : input clock frequency to the core.
+- baud-width: width, in bits, of the programmable divider used to scale
+       the input clock to SCLK.
+
+The clock-frequency and baud-width properties are needed only if the divider
+is programmable. They are not needed if the divider is fixed.

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index bb233a9cbad2fef09da95aef7225cad4e78c518d..8faa57a58dd1cf40baf9414a0c6ee89e5d83fb2a 100644 (file)
--- 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 86d1b5f9bbd9a9b93c91db63ce7af659b5f6c74c..c7e4c23c6f36a24311603670aedf9672e5635958 100644 (file)
--- 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 (file)
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);

diff --git a/include/linux/spi/spi_oc_tiny.h b/include/linux/spi/spi_oc_tiny.h
new file mode 100644 (file)
index 0000000..1ac529c
--- /dev/null
+++ b/include/linux/spi/spi_oc_tiny.h
@@ -0,0 +1,20 @@
+#ifndef _LINUX_SPI_SPI_OC_TINY_H
+#define _LINUX_SPI_SPI_OC_TINY_H
+
+/**
+ * struct tiny_spi_platform_data - platform data of the OpenCores tiny SPI
+ * @freq:      input clock freq to the core.
+ * @baudwidth: baud rate divider width of the core.
+ * @gpio_cs_count:     number of gpio pins used for chipselect.
+ * @gpio_cs:   array of gpio pins used for chipselect.
+ *
+ * freq and baudwidth are used only if the divider is programmable.
+ */
+struct tiny_spi_platform_data {
+       unsigned int freq;
+       unsigned int baudwidth;
+       unsigned int gpio_cs_count;
+       int *gpio_cs;
+};
+
+#endif /* _LINUX_SPI_SPI_OC_TINY_H */