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Date: Sun, 08 Mar 2009 12:03:47 +0200
From: Mike Rapoport <mike@...pulab.co.il>
To: David Brownell <david-b@...bell.net>
CC: Alessandro Zummo <alessandro.zummo@...ertech.it>,
rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
raph@...com, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] rtc-v3020: add ability to access v3020 chip with GPIOs
David,
David Brownell wrote:
> On Monday 02 March 2009, Mike Rapoport wrote:
>> +
>> +#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;
>> +};
>> +
>
>> +static struct v3020_gpio v3020_gpio[] = {
>> + { "RTC CS", 0 },
>> + { "RTC WR", 0 },
>> + { "RTC RD", 0 },
>> + { "RTC IO", 0 },
>> +};
>
> After Andrew's fault path cleanup it looks OK, but I see
> no point to that GPIO struct with the name. You know the
> name based on the position, if you ever need one. Take
> that away, and you can add my ack.
>
>
> Also, best not to have a single static struct; there's
> no need to add a driver restriction that there be only
> one of these chips in a system.
What about the below version?
> - Dave
>
Signed-off-by: Mike Rapoport <mike@...pulab.co.il>
CC: Alessandro Zummo <alessandro.zummo@...ertech.it>
CC: David Brownell <david-b@...bell.net>
CC: Andrew Morton <akpm@...ux-foundation.org>
---
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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