Re: [PATCH] rtc-v3020: add ability to access v3020 chip with GPIOs

From: David Brownell
Date: Thu Mar 19 2009 - 17:26:19 EST

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On Sunday 08 March 2009, Mike Rapoport wrote:

>
> What about the below version?

Looks OK.

> Signed-off-by: Mike Rapoport <mike@xxxxxxxxxxxxxx>
> CC: Alessandro Zummo <alessandro.zummo@xxxxxxxxxxxx>
> CC: David Brownell <david-b@xxxxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/rtc/rtc-v3020.c | 183 ++++++++++++++++++++++++++++++++++++++++-----
> include/linux/rtc-v3020.h | 6 ++
> 2 files changed, 169 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/rtc/rtc-v3020.c b/drivers/rtc/rtc-v3020.c
> index 66955cc..9f29929 100644
> --- a/drivers/rtc/rtc-v3020.c
> +++ b/drivers/rtc/rtc-v3020.c
> @@ -27,17 +27,155 @@
> #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 {
> + /* MMIO access */
> void __iomem *ioaddress;
> int leftshift;
> +
> + /* GPIO access */
> + unsigned int gpio[4];
> +
> + 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 const char *v3020_gpio_names[] = {
> + "RTC CS",
> + "RTC WR",
> + "RTC RD",
> + "RTC IO",
> +};
> +
> +static int v3020_gpio_map(struct v3020 *chip, struct platform_device *pdev,
> + struct v3020_platform_data *pdata)
> +{
> + int i, err;
> +
> + chip->gpio[V3020_CS] = pdata->gpio_cs;
> + chip->gpio[V3020_WR] = pdata->gpio_wr;
> + chip->gpio[V3020_RD] = pdata->gpio_rd;
> + chip->gpio[V3020_IO] = pdata->gpio_io;
> +
> + for (i = 0; i < ARRAY_SIZE(chip->gpio); i++) {
> + err = gpio_request(chip->gpio[i], v3020_gpio_names[i]);
> + if (err)
> + goto err_request;
> +
> + gpio_direction_output(chip->gpio[i], 1);
> + }
> +
> + return 0;
> +
> +err_request:
> + while (--i >= 0)
> + gpio_free(chip->gpio[i]);
> +
> + return err;
> +}
> +
> +static void v3020_gpio_unmap(struct v3020 *chip)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(chip->gpio); i++)
> + gpio_free(chip->gpio[i]);
> +}
> +
> +static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)
> +{
> + gpio_direction_output(chip->gpio[V3020_IO], bit);
> + gpio_set_value(chip->gpio[V3020_CS], 0);
> + gpio_set_value(chip->gpio[V3020_WR], 0);
> + udelay(1);
> + gpio_set_value(chip->gpio[V3020_WR], 1);
> + gpio_set_value(chip->gpio[V3020_CS], 1);
> +}
> +
> +static unsigned char v3020_gpio_read_bit(struct v3020 *chip)
> +{
> + int bit;
> +
> + gpio_direction_input(chip->gpio[V3020_IO]);
> + gpio_set_value(chip->gpio[V3020_CS], 0);
> + gpio_set_value(chip->gpio[V3020_RD], 0);
> + udelay(1);
> + bit = !!gpio_get_value(chip->gpio[V3020_IO]);
> + udelay(1);
> + gpio_set_value(chip->gpio[V3020_RD], 1);
> + gpio_set_value(chip->gpio[V3020_CS], 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 +184,7 @@ 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 +192,7 @@ 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 +205,14 @@ 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 +302,23 @@ 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 */
> @@ -196,10 +332,17 @@ 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,"
> - "data connected to D%d\n",
> - (unsigned long long)pdev->resource[0].start,
> - chip->leftshift);
> + if (pdata->use_gpio)
> + dev_info(&pdev->dev, "Chip available at GPIOs "
> + "%d, %d, %d, %d\n",
> + chip->gpio[V3020_CS], chip->gpio[V3020_WR],
> + chip->gpio[V3020_RD], chip->gpio[V3020_IO]);
> + 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);
>
> platform_set_drvdata(pdev, chip);
>
> @@ -214,7 +357,7 @@ 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 +372,7 @@ 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;
> diff --git a/include/linux/rtc-v3020.h b/include/linux/rtc-v3020.h
> index bf74e63..8ba646e 100644
> --- a/include/linux/rtc-v3020.h
> +++ b/include/linux/rtc-v3020.h
> @@ -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
> --
> 1.5.6.4
>
>
>
>
> --
> Sincerely yours,
> Mike.
>
>

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Next message: Mel Gorman: "Re: [PATCH 20/35] Use a pre-calculated value for num_online_nodes()"
Previous message: Serge E. Hallyn: "[PATCH 1/1] introduce user_ns inheritance in user-sched"
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