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Commit ce792580 authored by Thomas Chou's avatar Thomas Chou Committed by Grant Likely
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spi: add OpenCores tiny SPI driver 

This patch adds support of OpenCores tiny SPI driver.

http://opencores.org/project,tiny_spi



Signed-off-by: default avatarThomas Chou <thomas@wytron.com.tw>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 9bde36af

Documentation/devicetree/bindings/spi/spi_oc_tiny.txt

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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.

drivers/spi/Kconfig

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@@ -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

drivers/spi/Makefile

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@@ -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

drivers/spi/spi_oc_tiny.c

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/*

 * 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);

include/linux/spi/spi_oc_tiny.h

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#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 */