spi/clps711x: New SPI master driver

This patch add new driver for CLPS711X SPI master controller.
Due to platform limitations driver supports only 8 bit transfer mode.
Chip select control is handled via GPIO.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 296 insertions, 0 deletions

diff --git a/drivers/spi/spi-clps711x.c b/drivers/spi/spi-clps711x.c
new file mode 100644
index 00000000000..59677eb30f9
--- /dev/null
+++ b/drivers/spi/spi-clps711x.c
@@ -0,0 +1,296 @@
+/*
+ *  CLPS711X SPI bus driver
+ *
+ *  Copyright (C) 2012 Alexander Shiyan <shc_work@mail.ru>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/init.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/platform_data/spi-clps711x.h>
+
+#include <mach/hardware.h>
+
+#define DRIVER_NAME	"spi-clps711x"
+
+struct spi_clps711x_data {
+	struct completion	done;
+
+	struct clk		*spi_clk;
+	u32			max_speed_hz;
+
+	u8			*tx_buf;
+	u8			*rx_buf;
+	int			count;
+	int			len;
+
+	int			chipselect[0];
+};
+
+static int spi_clps711x_setup(struct spi_device *spi)
+{
+	struct spi_clps711x_data *hw = spi_master_get_devdata(spi->master);
+
+	if (spi->bits_per_word != 8) {
+		dev_err(&spi->dev, "Unsupported master bus width %i\n",
+			spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	/* We are expect that SPI-device is not selected */
+	gpio_direction_output(hw->chipselect[spi->chip_select],
+			      !(spi->mode & SPI_CS_HIGH));
+
+	return 0;
+}
+
+static void spi_clps711x_setup_mode(struct spi_device *spi)
+{
+	/* Setup edge for transfer */
+	if (spi->mode & SPI_CPHA)
+		clps_writew(clps_readw(SYSCON3) | SYSCON3_ADCCKNSEN, SYSCON3);
+	else
+		clps_writew(clps_readw(SYSCON3) & ~SYSCON3_ADCCKNSEN, SYSCON3);
+}
+
+static int spi_clps711x_setup_xfer(struct spi_device *spi,
+				   struct spi_transfer *xfer)
+{
+	u32 speed = xfer->speed_hz ? : spi->max_speed_hz;
+	u8 bpw = xfer->bits_per_word ? : spi->bits_per_word;
+	struct spi_clps711x_data *hw = spi_master_get_devdata(spi->master);
+
+	if (bpw != 8) {
+		dev_err(&spi->dev, "Unsupported master bus width %i\n", bpw);
+		return -EINVAL;
+	}
+
+	/* Setup SPI frequency divider */
+	if (!speed || (speed >= hw->max_speed_hz))
+		clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
+			    SYSCON1_ADCKSEL(3), SYSCON1);
+	else if (speed >= (hw->max_speed_hz / 2))
+		clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
+			    SYSCON1_ADCKSEL(2), SYSCON1);
+	else if (speed >= (hw->max_speed_hz / 8))
+		clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
+			    SYSCON1_ADCKSEL(1), SYSCON1);
+	else
+		clps_writel((clps_readl(SYSCON1) & ~SYSCON1_ADCKSEL_MASK) |
+			    SYSCON1_ADCKSEL(0), SYSCON1);
+
+	return 0;
+}
+
+static int spi_clps711x_transfer_one_message(struct spi_master *master,
+					     struct spi_message *msg)
+{
+	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
+	struct spi_transfer *xfer;
+	int status = 0, cs = hw->chipselect[msg->spi->chip_select];
+	u32 data;
+
+	spi_clps711x_setup_mode(msg->spi);
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (spi_clps711x_setup_xfer(msg->spi, xfer)) {
+			status = -EINVAL;
+			goto out_xfr;
+		}
+
+		gpio_set_value(cs, !!(msg->spi->mode & SPI_CS_HIGH));
+
+		INIT_COMPLETION(hw->done);
+
+		hw->count = 0;
+		hw->len = xfer->len;
+		hw->tx_buf = (u8 *)xfer->tx_buf;
+		hw->rx_buf = (u8 *)xfer->rx_buf;
+
+		/* Initiate transfer */
+		data = hw->tx_buf ? hw->tx_buf[hw->count] : 0;
+		clps_writel(data | SYNCIO_FRMLEN(8) | SYNCIO_TXFRMEN, SYNCIO);
+
+		wait_for_completion(&hw->done);
+
+		if (xfer->delay_usecs)
+			udelay(xfer->delay_usecs);
+
+		if (xfer->cs_change ||
+		    list_is_last(&xfer->transfer_list, &msg->transfers))
+			gpio_set_value(cs, !(msg->spi->mode & SPI_CS_HIGH));
+
+		msg->actual_length += xfer->len;
+	}
+
+out_xfr:
+	msg->status = status;
+	spi_finalize_current_message(master);
+
+	return 0;
+}
+
+static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
+{
+	struct spi_clps711x_data *hw = (struct spi_clps711x_data *)dev_id;
+	u32 data;
+
+	/* Handle RX */
+	data = clps_readb(SYNCIO);
+	if (hw->rx_buf)
+		hw->rx_buf[hw->count] = (u8)data;
+
+	hw->count++;
+
+	/* Handle TX */
+	if (hw->count < hw->len) {
+		data = hw->tx_buf ? hw->tx_buf[hw->count] : 0;
+		clps_writel(data | SYNCIO_FRMLEN(8) | SYNCIO_TXFRMEN, SYNCIO);
+	} else
+		complete(&hw->done);
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit spi_clps711x_probe(struct platform_device *pdev)
+{
+	int i, ret;
+	struct spi_master *master;
+	struct spi_clps711x_data *hw;
+	struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "No platform data supplied\n");
+		return -EINVAL;
+	}
+
+	if (pdata->num_chipselect < 1) {
+		dev_err(&pdev->dev, "At least one CS must be defined\n");
+		return -EINVAL;
+	}
+
+	master = spi_alloc_master(&pdev->dev,
+				  sizeof(struct spi_clps711x_data) +
+				  sizeof(int) * pdata->num_chipselect);
+	if (!master) {
+		dev_err(&pdev->dev, "SPI allocating memory error\n");
+		return -ENOMEM;
+	}
+
+	master->bus_num = pdev->id;
+	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
+	master->num_chipselect = pdata->num_chipselect;
+	master->setup = spi_clps711x_setup;
+	master->transfer_one_message = spi_clps711x_transfer_one_message;
+
+	hw = spi_master_get_devdata(master);
+
+	for (i = 0; i < master->num_chipselect; i++) {
+		hw->chipselect[i] = pdata->chipselect[i];
+		if (!gpio_is_valid(hw->chipselect[i])) {
+			dev_err(&pdev->dev, "Invalid CS GPIO %i\n", i);
+			ret = -EINVAL;
+			goto err_out;
+		}
+		if (gpio_request(hw->chipselect[i], DRIVER_NAME)) {
+			dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
+			ret = -EINVAL;
+			goto err_out;
+		}
+	}
+
+	hw->spi_clk = devm_clk_get(&pdev->dev, "spi");
+	if (IS_ERR(hw->spi_clk)) {
+		dev_err(&pdev->dev, "Can't get clocks\n");
+		ret = PTR_ERR(hw->spi_clk);
+		goto err_out;
+	}
+	hw->max_speed_hz = clk_get_rate(hw->spi_clk);
+
+	init_completion(&hw->done);
+	platform_set_drvdata(pdev, master);
+
+	/* Disable extended mode due hardware problems */
+	clps_writew(clps_readw(SYSCON3) & ~SYSCON3_ADCCON, SYSCON3);
+
+	/* Clear possible pending interrupt */
+	clps_readl(SYNCIO);
+
+	ret = devm_request_irq(&pdev->dev, IRQ_SSEOTI, spi_clps711x_isr, 0,
+			       dev_name(&pdev->dev), hw);
+	if (ret) {
+		dev_err(&pdev->dev, "Can't request IRQ\n");
+		clk_put(hw->spi_clk);
+		goto clk_out;
+	}
+
+	ret = spi_register_master(master);
+	if (!ret) {
+		dev_info(&pdev->dev,
+			 "SPI bus driver initialized. Master clock %u Hz\n",
+			 hw->max_speed_hz);
+		return 0;
+	}
+
+	dev_err(&pdev->dev, "Failed to register master\n");
+	devm_free_irq(&pdev->dev, IRQ_SSEOTI, hw);
+
+clk_out:
+	devm_clk_put(&pdev->dev, hw->spi_clk);
+
+err_out:
+	while (--i >= 0)
+		if (gpio_is_valid(hw->chipselect[i]))
+			gpio_free(hw->chipselect[i]);
+
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(master);
+	kfree(master);
+
+	return ret;
+}
+
+static int __devexit spi_clps711x_remove(struct platform_device *pdev)
+{
+	int i;
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
+
+	devm_free_irq(&pdev->dev, IRQ_SSEOTI, hw);
+
+	for (i = 0; i < master->num_chipselect; i++)
+		if (gpio_is_valid(hw->chipselect[i]))
+			gpio_free(hw->chipselect[i]);
+
+	devm_clk_put(&pdev->dev, hw->spi_clk);
+	platform_set_drvdata(pdev, NULL);
+	spi_unregister_master(master);
+	kfree(master);
+
+	return 0;
+}
+
+static struct platform_driver clps711x_spi_driver = {
+	.driver	= {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+	},
+	.probe	= spi_clps711x_probe,
+	.remove	= __devexit_p(spi_clps711x_remove),
+};
+module_platform_driver(clps711x_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("CLPS711X SPI bus driver");