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: Mike Rapoport <mike@compulab.co.il> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>hifive-unleashed-5.1
Mike Rapoport
Linus Torvalds
parent
c1c490e017
commit
96615841e1
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@ -27,17 +27,162 @@
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#include <linux/bcd.h>
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#include <linux/rtc-v3020.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/io.h>
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#undef DEBUG
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struct v3020;
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struct v3020_chip_ops {
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int (*map_io)(struct v3020 *chip, struct platform_device *pdev,
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struct v3020_platform_data *pdata);
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void (*unmap_io)(struct v3020 *chip);
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unsigned char (*read_bit)(struct v3020 *chip);
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void (*write_bit)(struct v3020 *chip, unsigned char bit);
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};
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#define V3020_CS 0
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#define V3020_WR 1
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#define V3020_RD 2
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#define V3020_IO 3
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struct v3020_gpio {
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const char *name;
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unsigned int gpio;
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};
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struct v3020 {
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/* MMIO access */
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void __iomem *ioaddress;
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int leftshift;
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/* GPIO access */
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struct v3020_gpio *gpio;
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struct v3020_chip_ops *ops;
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struct rtc_device *rtc;
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};
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static int v3020_mmio_map(struct v3020 *chip, struct platform_device *pdev,
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struct v3020_platform_data *pdata)
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{
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if (pdev->num_resources != 1)
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return -EBUSY;
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if (pdev->resource[0].flags != IORESOURCE_MEM)
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return -EBUSY;
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chip->leftshift = pdata->leftshift;
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chip->ioaddress = ioremap(pdev->resource[0].start, 1);
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if (chip->ioaddress == NULL)
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return -EBUSY;
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return 0;
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}
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static void v3020_mmio_unmap(struct v3020 *chip)
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{
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iounmap(chip->ioaddress);
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}
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static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)
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{
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writel(bit << chip->leftshift, chip->ioaddress);
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}
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static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
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{
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return readl(chip->ioaddress) & (1 << chip->leftshift);
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}
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static struct v3020_chip_ops v3020_mmio_ops = {
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.map_io = v3020_mmio_map,
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.unmap_io = v3020_mmio_unmap,
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.read_bit = v3020_mmio_read_bit,
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.write_bit = v3020_mmio_write_bit,
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};
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static struct v3020_gpio v3020_gpio[] = {
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{ "RTC CS", 0 },
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{ "RTC WR", 0 },
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{ "RTC RD", 0 },
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{ "RTC IO", 0 },
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};
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static int v3020_gpio_map(struct v3020 *chip, struct platform_device *pdev,
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struct v3020_platform_data *pdata)
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{
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int i, err;
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v3020_gpio[V3020_CS].gpio = pdata->gpio_cs;
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v3020_gpio[V3020_WR].gpio = pdata->gpio_wr;
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v3020_gpio[V3020_RD].gpio = pdata->gpio_rd;
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v3020_gpio[V3020_IO].gpio = pdata->gpio_io;
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for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++) {
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err = gpio_request(v3020_gpio[i].gpio, v3020_gpio[i].name);
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if (err)
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goto err_request;
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gpio_direction_output(v3020_gpio[i].gpio, 1);
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}
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chip->gpio = v3020_gpio;
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return 0;
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err_request:
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while (--i >= 0)
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gpio_free(v3020_gpio[i].gpio);
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return err;
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}
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static void v3020_gpio_unmap(struct v3020 *chip)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++)
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gpio_free(v3020_gpio[i].gpio);
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}
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static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)
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{
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gpio_direction_output(chip->gpio[V3020_IO].gpio, bit);
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gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
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gpio_set_value(chip->gpio[V3020_WR].gpio, 0);
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udelay(1);
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gpio_set_value(chip->gpio[V3020_WR].gpio, 1);
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gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
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}
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static unsigned char v3020_gpio_read_bit(struct v3020 *chip)
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{
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int bit;
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gpio_direction_input(chip->gpio[V3020_IO].gpio);
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gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
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gpio_set_value(chip->gpio[V3020_RD].gpio, 0);
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udelay(1);
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bit = !!gpio_get_value(chip->gpio[V3020_IO].gpio);
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udelay(1);
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gpio_set_value(chip->gpio[V3020_RD].gpio, 1);
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gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
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return bit;
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}
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static struct v3020_chip_ops v3020_gpio_ops = {
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.map_io = v3020_gpio_map,
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.unmap_io = v3020_gpio_unmap,
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.read_bit = v3020_gpio_read_bit,
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.write_bit = v3020_gpio_write_bit,
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};
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static void v3020_set_reg(struct v3020 *chip, unsigned char address,
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unsigned char data)
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{
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@ -46,7 +191,7 @@ static void v3020_set_reg(struct v3020 *chip, unsigned char address,
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tmp = address;
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for (i = 0; i < 4; i++) {
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writel((tmp & 1) << chip->leftshift, chip->ioaddress);
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chip->ops->write_bit(chip, (tmp & 1));
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tmp >>= 1;
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udelay(1);
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}
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@ -54,7 +199,7 @@ static void v3020_set_reg(struct v3020 *chip, unsigned char address,
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/* Commands dont have data */
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if (!V3020_IS_COMMAND(address)) {
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for (i = 0; i < 8; i++) {
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writel((data & 1) << chip->leftshift, chip->ioaddress);
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chip->ops->write_bit(chip, (data & 1));
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data >>= 1;
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udelay(1);
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}
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@ -67,14 +212,14 @@ static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address)
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int i;
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for (i = 0; i < 4; i++) {
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writel((address & 1) << chip->leftshift, chip->ioaddress);
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chip->ops->write_bit(chip, (address & 1));
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address >>= 1;
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udelay(1);
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}
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for (i = 0; i < 8; i++) {
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data >>= 1;
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if (readl(chip->ioaddress) & (1 << chip->leftshift))
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if (chip->ops->read_bit(chip))
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data |= 0x80;
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udelay(1);
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}
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@ -164,25 +309,23 @@ static int rtc_probe(struct platform_device *pdev)
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int i;
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int temp;
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if (pdev->num_resources != 1)
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return -EBUSY;
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if (pdev->resource[0].flags != IORESOURCE_MEM)
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return -EBUSY;
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chip = kzalloc(sizeof *chip, GFP_KERNEL);
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if (!chip)
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return -ENOMEM;
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chip->leftshift = pdata->leftshift;
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chip->ioaddress = ioremap(pdev->resource[0].start, 1);
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if (chip->ioaddress == NULL)
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if (pdata->use_gpio)
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chip->ops = &v3020_gpio_ops;
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else
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chip->ops = &v3020_mmio_ops;
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retval = chip->ops->map_io(chip, pdev, pdata);
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if (retval)
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goto err_chip;
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/* Make sure the v3020 expects a communication cycle
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* by reading 8 times */
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for (i = 0; i < 8; i++)
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temp = readl(chip->ioaddress);
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temp = chip->ops->read_bit(chip);
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/* Test chip by doing a write/read sequence
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* to the chip ram */
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@ -196,10 +339,17 @@ static int rtc_probe(struct platform_device *pdev)
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* are all disabled */
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v3020_set_reg(chip, V3020_STATUS_0, 0x0);
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dev_info(&pdev->dev, "Chip available at physical address 0x%llx,"
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"data connected to D%d\n",
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(unsigned long long)pdev->resource[0].start,
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chip->leftshift);
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if (pdata->use_gpio)
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dev_info(&pdev->dev, "Chip available at GPIOs "
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"%d, %d, %d, %d\n",
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chip->gpio[V3020_CS].gpio, chip->gpio[V3020_WR].gpio,
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chip->gpio[V3020_RD].gpio, chip->gpio[V3020_IO].gpio);
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else
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dev_info(&pdev->dev, "Chip available at "
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"physical address 0x%llx,"
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"data connected to D%d\n",
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(unsigned long long)pdev->resource[0].start,
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chip->leftshift);
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platform_set_drvdata(pdev, chip);
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@ -214,7 +364,7 @@ static int rtc_probe(struct platform_device *pdev)
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return 0;
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err_io:
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iounmap(chip->ioaddress);
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chip->ops->unmap_io(chip);
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err_chip:
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kfree(chip);
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@ -229,7 +379,7 @@ static int rtc_remove(struct platform_device *dev)
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if (rtc)
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rtc_device_unregister(rtc);
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iounmap(chip->ioaddress);
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chip->ops->unmap_io(chip);
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kfree(chip);
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return 0;
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@ -14,6 +14,12 @@
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* is used depends on the board. */
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struct v3020_platform_data {
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int leftshift; /* (1<<(leftshift)) & readl() */
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int use_gpio:1;
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unsigned int gpio_cs;
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unsigned int gpio_wr;
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unsigned int gpio_rd;
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unsigned int gpio_io;
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};
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#define V3020_STATUS_0 0x00
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