Commit 96615841 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

rtc-v3020: add ability to access v3020 chip with GPIOs 



The v3020 RTC can be connected to GPIOs as well as to memory-like
interface.  Add ability to use GPIO bit-bang for v3020 read-write access.

[akpm@linux-foundation.org: fix off-by-one in error path]
Signed-off-by: default avatarMike Rapoport <mike@compulab.co.il>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c1c490e0

drivers/rtc/rtc-v3020.c

+170 −20
Original line number Diff line number Diff line
@@ -27,17 +27,162 @@ 
#include <linux/bcd.h>

#include <linux/rtc-v3020.h>

#include <linux/delay.h>

#include <linux/gpio.h>



#include <linux/io.h>



#undef DEBUG



struct v3020;



struct v3020_chip_ops {

	int (*map_io)(struct v3020 *chip, struct platform_device *pdev,

		      struct v3020_platform_data *pdata);

	void (*unmap_io)(struct v3020 *chip);

	unsigned char (*read_bit)(struct v3020 *chip);

	void (*write_bit)(struct v3020 *chip, unsigned char bit);

};



#define V3020_CS	0

#define V3020_WR	1

#define V3020_RD	2

#define V3020_IO	3



struct v3020_gpio {

	const char *name;

	unsigned int gpio;

};



struct v3020 {

	/* MMIO access */

	void __iomem *ioaddress;

	int leftshift;



	/* GPIO access */

	struct v3020_gpio *gpio;



	struct v3020_chip_ops *ops;



	struct rtc_device *rtc;

};





static int v3020_mmio_map(struct v3020 *chip, struct platform_device *pdev,

			  struct v3020_platform_data *pdata)

{

	if (pdev->num_resources != 1)

		return -EBUSY;



	if (pdev->resource[0].flags != IORESOURCE_MEM)

		return -EBUSY;



	chip->leftshift = pdata->leftshift;

	chip->ioaddress = ioremap(pdev->resource[0].start, 1);

	if (chip->ioaddress == NULL)

		return -EBUSY;



	return 0;

}



static void v3020_mmio_unmap(struct v3020 *chip)

{

	iounmap(chip->ioaddress);

}



static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)

{

	writel(bit << chip->leftshift, chip->ioaddress);

}



static unsigned char v3020_mmio_read_bit(struct v3020 *chip)

{

	return readl(chip->ioaddress) & (1 << chip->leftshift);

}



static struct v3020_chip_ops v3020_mmio_ops = {

	.map_io		= v3020_mmio_map,

	.unmap_io	= v3020_mmio_unmap,

	.read_bit	= v3020_mmio_read_bit,

	.write_bit	= v3020_mmio_write_bit,

};



static struct v3020_gpio v3020_gpio[] = {

	{ "RTC CS", 0 },

	{ "RTC WR", 0 },

	{ "RTC RD", 0 },

	{ "RTC IO", 0 },

};



static int v3020_gpio_map(struct v3020 *chip, struct platform_device *pdev,

			  struct v3020_platform_data *pdata)

{

	int i, err;



	v3020_gpio[V3020_CS].gpio = pdata->gpio_cs;

	v3020_gpio[V3020_WR].gpio = pdata->gpio_wr;

	v3020_gpio[V3020_RD].gpio = pdata->gpio_rd;

	v3020_gpio[V3020_IO].gpio = pdata->gpio_io;



	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++) {

		err = gpio_request(v3020_gpio[i].gpio, v3020_gpio[i].name);

		if (err)

			goto err_request;



		gpio_direction_output(v3020_gpio[i].gpio, 1);

	}



	chip->gpio = v3020_gpio;



	return 0;



err_request:

	while (--i >= 0)

		gpio_free(v3020_gpio[i].gpio);



	return err;

}



static void v3020_gpio_unmap(struct v3020 *chip)

{

	int i;



	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++)

		gpio_free(v3020_gpio[i].gpio);

}



static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)

{

	gpio_direction_output(chip->gpio[V3020_IO].gpio, bit);

	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);

	gpio_set_value(chip->gpio[V3020_WR].gpio, 0);

	udelay(1);

	gpio_set_value(chip->gpio[V3020_WR].gpio, 1);

	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);

}



static unsigned char v3020_gpio_read_bit(struct v3020 *chip)

{

	int bit;



	gpio_direction_input(chip->gpio[V3020_IO].gpio);

	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);

	gpio_set_value(chip->gpio[V3020_RD].gpio, 0);

	udelay(1);

	bit = !!gpio_get_value(chip->gpio[V3020_IO].gpio);

	udelay(1);

	gpio_set_value(chip->gpio[V3020_RD].gpio, 1);

	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);



	return bit;

}



static struct v3020_chip_ops v3020_gpio_ops = {

	.map_io		= v3020_gpio_map,

	.unmap_io	= v3020_gpio_unmap,

	.read_bit	= v3020_gpio_read_bit,

	.write_bit	= v3020_gpio_write_bit,

};



static void v3020_set_reg(struct v3020 *chip, unsigned char address,

			unsigned char data)

{
@@ -46,7 +191,7 @@ static void v3020_set_reg(struct v3020 *chip, unsigned char address, 


	tmp = address;

	for (i = 0; i < 4; i++) {

		writel((tmp & 1) << chip->leftshift, chip->ioaddress);

		chip->ops->write_bit(chip, (tmp & 1));

		tmp >>= 1;

		udelay(1);

	}
@@ -54,7 +199,7 @@ static void v3020_set_reg(struct v3020 *chip, unsigned char address, 
	/* Commands dont have data */

	if (!V3020_IS_COMMAND(address)) {

		for (i = 0; i < 8; i++) {

			writel((data & 1) << chip->leftshift, chip->ioaddress);

			chip->ops->write_bit(chip, (data & 1));

			data >>= 1;

			udelay(1);

		}
@@ -67,14 +212,14 @@ static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address) 
	int i;



	for (i = 0; i < 4; i++) {

		writel((address & 1) << chip->leftshift, chip->ioaddress);

		chip->ops->write_bit(chip, (address & 1));

		address >>= 1;

		udelay(1);

	}



	for (i = 0; i < 8; i++) {

		data >>= 1;

		if (readl(chip->ioaddress) & (1 << chip->leftshift))

		if (chip->ops->read_bit(chip))

			data |= 0x80;

		udelay(1);

	}
@@ -164,25 +309,23 @@ static int rtc_probe(struct platform_device *pdev) 
	int i;

	int temp;



	if (pdev->num_resources != 1)

		return -EBUSY;



	if (pdev->resource[0].flags != IORESOURCE_MEM)

		return -EBUSY;



	chip = kzalloc(sizeof *chip, GFP_KERNEL);

	if (!chip)

		return -ENOMEM;



	chip->leftshift = pdata->leftshift;

	chip->ioaddress = ioremap(pdev->resource[0].start, 1);

	if (chip->ioaddress == NULL)

	if (pdata->use_gpio)

		chip->ops = &v3020_gpio_ops;

	else

		chip->ops = &v3020_mmio_ops;



	retval = chip->ops->map_io(chip, pdev, pdata);

	if (retval)

		goto err_chip;



	/* Make sure the v3020 expects a communication cycle

	 * by reading 8 times */

	for (i = 0; i < 8; i++)

		temp = readl(chip->ioaddress);

		temp = chip->ops->read_bit(chip);



	/* Test chip by doing a write/read sequence

	 * to the chip ram */
@@ -196,7 +339,14 @@ static int rtc_probe(struct platform_device *pdev) 
	 * are all disabled */

	v3020_set_reg(chip, V3020_STATUS_0, 0x0);



	dev_info(&pdev->dev, "Chip available at physical address 0x%llx,"

	if (pdata->use_gpio)

		dev_info(&pdev->dev, "Chip available at GPIOs "

			 "%d, %d, %d, %d\n",

			 chip->gpio[V3020_CS].gpio, chip->gpio[V3020_WR].gpio,

			 chip->gpio[V3020_RD].gpio, chip->gpio[V3020_IO].gpio);

	else

		dev_info(&pdev->dev, "Chip available at "

			 "physical address 0x%llx,"

			 "data connected to D%d\n",

			 (unsigned long long)pdev->resource[0].start,

			 chip->leftshift);
@@ -214,7 +364,7 @@ static int rtc_probe(struct platform_device *pdev) 
	return 0;



err_io:

	iounmap(chip->ioaddress);

	chip->ops->unmap_io(chip);

err_chip:

	kfree(chip);
@@ -229,7 +379,7 @@ static int rtc_remove(struct platform_device *dev) 
	if (rtc)

		rtc_device_unregister(rtc);



	iounmap(chip->ioaddress);

	chip->ops->unmap_io(chip);

	kfree(chip);



	return 0;

include/linux/rtc-v3020.h

+6 −0
Original line number Diff line number Diff line
@@ -14,6 +14,12 @@ 
 * is used depends on the board. */

struct v3020_platform_data {

	int leftshift; /* (1<<(leftshift)) & readl() */



	int use_gpio:1;

	unsigned int gpio_cs;

	unsigned int gpio_wr;

	unsigned int gpio_rd;

	unsigned int gpio_io;

};



#define V3020_STATUS_0	0x00

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