Re: [PATCH v2 0/4] Move plat-mxc gpio driver into drivers/gpio

From: Shawn Guo
Date: Fri Jun 03 2011 - 10:31:08 EST

Hi Russell,

On Fri, Jun 03, 2011 at 08:52:01AM +0100, Russell King - ARM Linux wrote:
> On Thu, Jun 02, 2011 at 11:33:48AM +0800, Shawn Guo wrote:
> > arch/arm/plat-mxc/gpio.c | 361 -------------------
> > drivers/gpio/gpio-mxc.c | 433 +++++++++++++++++++++++
>
My bad here. I should have used 'git diff --stat -M' to show the
the following.

.../arm/plat-mxc/gpio.c => drivers/gpio/gpio-mxc.c | 216 +++++++++++++-------

> I'm wondering why just moving this driver into drivers/gpio has
> resulted in it growing by 72 lines - and it's not clear from the
> diffs why that is because of the way they're broken up.
>
Yes, I agree. But when I did something like that to ease the review,
people think it's not necessary :)

http://permalink.gmane.org/gmane.linux.kernel/1143257

> Would it not be better to have the first patch to merely move
> arch/arm/plat-mxc/gpio.c to drivers/gpio/gpio-mxc.c, making whatever
> config changes are necessary. Then subsequent patches should change
> drivers/gpio/gpio-mxc.c as required - which means we can see what
> changes are being made.
>
Yes, I agree this is the best practice. Will do it in the future
posts.

To answer your question about 72 lines growing, here is what copied
from patch #1 commit message.

--- quote begins ---
Add gpio-mxc driver by copying arch/arm/plat-mxc/gpio.c into
drivers/gpio with the following changes.

* Use readl/writel to replace mach-specific accessors
__raw_readl/__raw_writel

* Migrate to platform driver by adding .probe function

* Add a list to save all mx2 ports references, so that
mx2_gpio_irq_handler can walk through all interrupt status
registers
--- quote ends ---

And the following is what the changes are exactly.

--- arch/arm/plat-mxc/gpio.c 2011-06-03 22:25:56.358274709 +0800
+++ drivers/gpio/gpio-mxc.c 2011-06-01 18:38:21.410182809 +0800
@@ -24,11 +24,28 @@
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/gpio.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
#include <mach/hardware.h>
#include <asm-generic/bug.h>

-static struct mxc_gpio_port *mxc_gpio_ports;
-static int gpio_table_size;
+struct mxc_gpio_port {
+ struct list_head node;
+ void __iomem *base;
+ int irq;
+ int irq_high;
+ int virtual_irq_start;
+ struct gpio_chip chip;
+ u32 both_edges;
+ spinlock_t lock;
+};
+
+/*
+ * MX2 has one interrupt *for all* gpio ports. The list is used
+ * to save the references to all ports, so that mx2_gpio_irq_handler
+ * can walk through all interrupt status registers.
+ */
+static LIST_HEAD(mxc_gpio_ports);

#define cpu_is_mx1_mx2() (cpu_is_mx1() || cpu_is_mx2())

@@ -50,7 +67,7 @@ static int gpio_table_size;

static void _clear_gpio_irqstatus(struct mxc_gpio_port *port, u32 index)
{
- __raw_writel(1 << index, port->base + GPIO_ISR);
+ writel(1 << index, port->base + GPIO_ISR);
}

static void _set_gpio_irqenable(struct mxc_gpio_port *port, u32 index,
@@ -58,27 +75,30 @@ static void _set_gpio_irqenable(struct m
{
u32 l;

- l = __raw_readl(port->base + GPIO_IMR);
+ l = readl(port->base + GPIO_IMR);
l = (l & (~(1 << index))) | (!!enable << index);
- __raw_writel(l, port->base + GPIO_IMR);
+ writel(l, port->base + GPIO_IMR);
}

static void gpio_ack_irq(struct irq_data *d)
{
+ struct mxc_gpio_port *port = irq_data_get_irq_chip_data(d);
u32 gpio = irq_to_gpio(d->irq);
- _clear_gpio_irqstatus(&mxc_gpio_ports[gpio / 32], gpio & 0x1f);
+ _clear_gpio_irqstatus(port, gpio & 0x1f);
}

static void gpio_mask_irq(struct irq_data *d)
{
+ struct mxc_gpio_port *port = irq_data_get_irq_chip_data(d);
u32 gpio = irq_to_gpio(d->irq);
- _set_gpio_irqenable(&mxc_gpio_ports[gpio / 32], gpio & 0x1f, 0);
+ _set_gpio_irqenable(port, gpio & 0x1f, 0);
}

static void gpio_unmask_irq(struct irq_data *d)
{
+ struct mxc_gpio_port *port = irq_data_get_irq_chip_data(d);
u32 gpio = irq_to_gpio(d->irq);
- _set_gpio_irqenable(&mxc_gpio_ports[gpio / 32], gpio & 0x1f, 1);
+ _set_gpio_irqenable(port, gpio & 0x1f, 1);
}

static int mxc_gpio_get(struct gpio_chip *chip, unsigned offset);
@@ -86,7 +106,7 @@ static int mxc_gpio_get(struct gpio_chip
static int gpio_set_irq_type(struct irq_data *d, u32 type)
{
u32 gpio = irq_to_gpio(d->irq);
- struct mxc_gpio_port *port = &mxc_gpio_ports[gpio / 32];
+ struct mxc_gpio_port *port = irq_data_get_irq_chip_data(d);
u32 bit, val;
int edge;
void __iomem *reg = port->base;
@@ -122,8 +142,8 @@ static int gpio_set_irq_type(struct irq_

reg += GPIO_ICR1 + ((gpio & 0x10) >> 2); /* lower or upper register */
bit = gpio & 0xf;
- val = __raw_readl(reg) & ~(0x3 << (bit << 1));
- __raw_writel(val | (edge << (bit << 1)), reg);
+ val = readl(reg) & ~(0x3 << (bit << 1));
+ writel(val | (edge << (bit << 1)), reg);
_clear_gpio_irqstatus(port, gpio & 0x1f);

return 0;
@@ -137,7 +157,7 @@ static void mxc_flip_edge(struct mxc_gpi

reg += GPIO_ICR1 + ((gpio & 0x10) >> 2); /* lower or upper register */
bit = gpio & 0xf;
- val = __raw_readl(reg);
+ val = readl(reg);
edge = (val >> (bit << 1)) & 3;
val &= ~(0x3 << (bit << 1));
if (edge == GPIO_INT_HIGH_LEV) {
@@ -151,7 +171,7 @@ static void mxc_flip_edge(struct mxc_gpi
gpio, edge);
return;
}
- __raw_writel(val | (edge << (bit << 1)), reg);
+ writel(val | (edge << (bit << 1)), reg);
}

/* handle 32 interrupts in one status register */
@@ -177,8 +197,7 @@ static void mx3_gpio_irq_handler(u32 irq
u32 irq_stat;
struct mxc_gpio_port *port = irq_get_handler_data(irq);

- irq_stat = __raw_readl(port->base + GPIO_ISR) &
- __raw_readl(port->base + GPIO_IMR);
+ irq_stat = readl(port->base + GPIO_ISR) & readl(port->base + GPIO_IMR);

mxc_gpio_irq_handler(port, irq_stat);
}
@@ -186,19 +205,18 @@ static void mx3_gpio_irq_handler(u32 irq
/* MX2 has one interrupt *for all* gpio ports */
static void mx2_gpio_irq_handler(u32 irq, struct irq_desc *desc)
{
- int i;
u32 irq_msk, irq_stat;
- struct mxc_gpio_port *port = irq_get_handler_data(irq);
+ struct mxc_gpio_port *port;

/* walk through all interrupt status registers */
- for (i = 0; i < gpio_table_size; i++) {
- irq_msk = __raw_readl(port[i].base + GPIO_IMR);
+ list_for_each_entry(port, &mxc_gpio_ports, node) {
+ irq_msk = readl(port->base + GPIO_IMR);
if (!irq_msk)
continue;

- irq_stat = __raw_readl(port[i].base + GPIO_ISR) & irq_msk;
+ irq_stat = readl(port->base + GPIO_ISR) & irq_msk;
if (irq_stat)
- mxc_gpio_irq_handler(&port[i], irq_stat);
+ mxc_gpio_irq_handler(port, irq_stat);
}
}

@@ -215,7 +233,7 @@ static int gpio_set_wake_irq(struct irq_
{
u32 gpio = irq_to_gpio(d->irq);
u32 gpio_idx = gpio & 0x1F;
- struct mxc_gpio_port *port = &mxc_gpio_ports[gpio / 32];
+ struct mxc_gpio_port *port = irq_data_get_irq_chip_data(d);

if (enable) {
if (port->irq_high && (gpio_idx >= 16))
@@ -250,12 +268,12 @@ static void _set_gpio_direction(struct g
unsigned long flags;

spin_lock_irqsave(&port->lock, flags);
- l = __raw_readl(port->base + GPIO_GDIR);
+ l = readl(port->base + GPIO_GDIR);
if (dir)
l |= 1 << offset;
else
l &= ~(1 << offset);
- __raw_writel(l, port->base + GPIO_GDIR);
+ writel(l, port->base + GPIO_GDIR);
spin_unlock_irqrestore(&port->lock, flags);
}

@@ -268,8 +286,8 @@ static void mxc_gpio_set(struct gpio_chi
unsigned long flags;

spin_lock_irqsave(&port->lock, flags);
- l = (__raw_readl(reg) & (~(1 << offset))) | (!!value << offset);
- __raw_writel(l, reg);
+ l = (readl(reg) & (~(1 << offset))) | (!!value << offset);
+ writel(l, reg);
spin_unlock_irqrestore(&port->lock, flags);
}

@@ -278,7 +296,7 @@ static int mxc_gpio_get(struct gpio_chip
struct mxc_gpio_port *port =
container_of(chip, struct mxc_gpio_port, chip);

- return (__raw_readl(port->base + GPIO_PSR) >> offset) & 1;
+ return (readl(port->base + GPIO_PSR) >> offset) & 1;
}

static int mxc_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
@@ -301,61 +319,115 @@ static int mxc_gpio_direction_output(str
*/
static struct lock_class_key gpio_lock_class;

-int __init mxc_gpio_init(struct mxc_gpio_port *port, int cnt)
+static int __devinit mxc_gpio_probe(struct platform_device *pdev)
{
- int i, j;
+ struct mxc_gpio_port *port;
+ struct resource *iores;
+ int err, i;
+
+ port = kzalloc(sizeof(struct mxc_gpio_port), GFP_KERNEL);
+ if (!port)
+ return -ENOMEM;
+
+ port->virtual_irq_start = MXC_GPIO_IRQ_START + pdev->id * 32;
+
+ iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!iores) {
+ err = -ENODEV;
+ goto out_kfree;
+ }

- /* save for local usage */
- mxc_gpio_ports = port;
- gpio_table_size = cnt;
-
- printk(KERN_INFO "MXC GPIO hardware\n");
-
- for (i = 0; i < cnt; i++) {
- /* disable the interrupt and clear the status */
- __raw_writel(0, port[i].base + GPIO_IMR);
- __raw_writel(~0, port[i].base + GPIO_ISR);
- for (j = port[i].virtual_irq_start;
- j < port[i].virtual_irq_start + 32; j++) {
- irq_set_lockdep_class(j, &gpio_lock_class);
- irq_set_chip_and_handler(j, &gpio_irq_chip,
- handle_level_irq);
- set_irq_flags(j, IRQF_VALID);
- }
+ if (!request_mem_region(iores->start, resource_size(iores),
+ pdev->name)) {
+ err = -EBUSY;
+ goto out_kfree;
+ }

- /* register gpio chip */
- port[i].chip.direction_input = mxc_gpio_direction_input;
- port[i].chip.direction_output = mxc_gpio_direction_output;
- port[i].chip.get = mxc_gpio_get;
- port[i].chip.set = mxc_gpio_set;
- port[i].chip.base = i * 32;
- port[i].chip.ngpio = 32;
-
- spin_lock_init(&port[i].lock);
-
- /* its a serious configuration bug when it fails */
- BUG_ON( gpiochip_add(&port[i].chip) < 0 );
-
- if (cpu_is_mx1() || cpu_is_mx3() || cpu_is_mx25() || cpu_is_mx51()) {
- /* setup one handler for each entry */
- irq_set_chained_handler(port[i].irq,
- mx3_gpio_irq_handler);
- irq_set_handler_data(port[i].irq, &port[i]);
- if (port[i].irq_high) {
- /* setup handler for GPIO 16 to 31 */
- irq_set_chained_handler(port[i].irq_high,
- mx3_gpio_irq_handler);
- irq_set_handler_data(port[i].irq_high,
- &port[i]);
- }
- }
+ port->base = ioremap(iores->start, resource_size(iores));
+ if (!port->base) {
+ err = -ENOMEM;
+ goto out_release_mem;
+ }
+
+ port->irq_high = platform_get_irq(pdev, 1);
+ port->irq = platform_get_irq(pdev, 0);
+ if (port->irq < 0) {
+ err = -EINVAL;
+ goto out_iounmap;
+ }
+
+ /* disable the interrupt and clear the status */
+ writel(0, port->base + GPIO_IMR);
+ writel(~0, port->base + GPIO_ISR);
+
+ for (i = port->virtual_irq_start;
+ i < port->virtual_irq_start + 32; i++) {
+ irq_set_lockdep_class(i, &gpio_lock_class);
+ irq_set_chip_and_handler(i, &gpio_irq_chip, handle_level_irq);
+ set_irq_flags(i, IRQF_VALID);
+ irq_set_chip_data(i, port);
}

if (cpu_is_mx2()) {
/* setup one handler for all GPIO interrupts */
- irq_set_chained_handler(port[0].irq, mx2_gpio_irq_handler);
- irq_set_handler_data(port[0].irq, port);
+ if (pdev->id == 0)
+ irq_set_chained_handler(port->irq,
+ mx2_gpio_irq_handler);
+ } else {
+ /* setup one handler for each entry */
+ irq_set_chained_handler(port->irq, mx3_gpio_irq_handler);
+ irq_set_handler_data(port->irq, port);
+ if (port->irq_high > 0) {
+ /* setup handler for GPIO 16 to 31 */
+ irq_set_chained_handler(port->irq_high,
+ mx3_gpio_irq_handler);
+ irq_set_handler_data(port->irq_high, port);
+ }
}

+ /* register gpio chip */
+ port->chip.direction_input = mxc_gpio_direction_input;
+ port->chip.direction_output = mxc_gpio_direction_output;
+ port->chip.get = mxc_gpio_get;
+ port->chip.set = mxc_gpio_set;
+ port->chip.base = pdev->id * 32;
+ port->chip.ngpio = 32;
+
+ spin_lock_init(&port->lock);
+
+ err = gpiochip_add(&port->chip);
+ if (err)
+ goto out_iounmap;
+
+ list_add_tail(&port->node, &mxc_gpio_ports);
+
return 0;
+
+out_iounmap:
+ iounmap(port->base);
+out_release_mem:
+ release_mem_region(iores->start, resource_size(iores));
+out_kfree:
+ kfree(port);
+ dev_info(&pdev->dev, "%s failed with errno %d\n", __func__, err);
+ return err;
}
+
+static struct platform_driver mxc_gpio_driver = {
+ .driver = {
+ .name = "gpio-mxc",
+ },
+ .probe = mxc_gpio_probe,
+};
+
+static int __init gpio_mxc_init(void)
+{
+ return platform_driver_register(&mxc_gpio_driver);
+}
+postcore_initcall(gpio_mxc_init);
+
+MODULE_AUTHOR("Freescale Semiconductor, "
+ "Daniel Mack <danielncaiaq.de>, "
+ "Juergen Beisert <kernel@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Freescale MXC GPIO");
+MODULE_LICENSE("GPL");

--
Regards,
Shawn

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