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powerpc/qe: Implement QE Pin Multiplexing API 

With this API we're able to set a QE pin to the GPIO mode or a dedicated
peripheral function.

The API relies on the fact that QE gpio controllers are registered. If
they aren't, the API won't work (gracefully though).

There is one caveat though: if anybody occupied the node->data before us,
or overwrote it, then bad things will happen. Luckily this is all in the
platform code that we fully control, so this should never happen.

I could implement more checks (for example we could create a list of
successfully registered QE controllers, and compare the node->data in the
qe_pin_request()), but this is unneeded if nobody is going to do silly
things behind our back.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This commit is contained in:
Anton Vorontsov 2008-12-03 22:27:38 +03:00 committed by Kumar Gala
parent 78c7705037
commit 1b9e89046c
2 changed files with 216 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
arch/powerpc/include/asm/qe.h
View File

@ -17,6 +17,8 @@
#ifdef __KERNEL__
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <asm/cpm.h>
#include <asm/immap_qe.h>
@ -112,6 +114,25 @@ extern int par_io_config_pin(u8 port, u8 pin, int dir, int open_drain,
int assignment, int has_irq);
extern int par_io_data_set(u8 port, u8 pin, u8 val);
/*
* Pin multiplexing functions.
*/
struct qe_pin;
#ifdef CONFIG_QE_GPIO
extern struct qe_pin *qe_pin_request(struct device_node *np, int index);
extern void qe_pin_free(struct qe_pin *qe_pin);
extern void qe_pin_set_gpio(struct qe_pin *qe_pin);
extern void qe_pin_set_dedicated(struct qe_pin *pin);
#else
static inline struct qe_pin *qe_pin_request(struct device_node *np, int index)
{
return ERR_PTR(-ENOSYS);
}
static inline void qe_pin_free(struct qe_pin *qe_pin) {}
static inline void qe_pin_set_gpio(struct qe_pin *qe_pin) {}
static inline void qe_pin_set_dedicated(struct qe_pin *pin) {}
#endif /* CONFIG_QE_GPIO */
/* QE internal API */
int qe_issue_cmd(u32 cmd, u32 device, u8 mcn_protocol, u32 cmd_input);
enum qe_clock qe_clock_source(const char *source);

195
arch/powerpc/sysdev/qe_lib/gpio.c
View File

@ -14,6 +14,7 @@
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
@ -24,8 +25,14 @@ struct qe_gpio_chip {
struct of_mm_gpio_chip mm_gc;
spinlock_t lock;
unsigned long pin_flags[QE_PIO_PINS];
#define QE_PIN_REQUESTED 0
/* shadowed data register to clear/set bits safely */
u32 cpdata;
/* saved_regs used to restore dedicated functions */
struct qe_pio_regs saved_regs;
};
static inline struct qe_gpio_chip *
@ -40,6 +47,12 @@ static void qe_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
struct qe_pio_regs __iomem *regs = mm_gc->regs;
qe_gc->cpdata = in_be32(&regs->cpdata);
qe_gc->saved_regs.cpdata = qe_gc->cpdata;
qe_gc->saved_regs.cpdir1 = in_be32(&regs->cpdir1);
qe_gc->saved_regs.cpdir2 = in_be32(&regs->cpdir2);
qe_gc->saved_regs.cppar1 = in_be32(&regs->cppar1);
qe_gc->saved_regs.cppar2 = in_be32(&regs->cppar2);
qe_gc->saved_regs.cpodr = in_be32(&regs->cpodr);
}
static int qe_gpio_get(struct gpio_chip *gc, unsigned int gpio)
@ -103,6 +116,188 @@ static int qe_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
return 0;
}
struct qe_pin {
/*
* The qe_gpio_chip name is unfortunate, we should change that to
* something like qe_pio_controller. Someday.
*/
struct qe_gpio_chip *controller;
int num;
};
/**
* qe_pin_request - Request a QE pin
* @np: device node to get a pin from
* @index: index of a pin in the device tree
* Context: non-atomic
*
* This function return qe_pin so that you could use it with the rest of
* the QE Pin Multiplexing API.
*/
struct qe_pin *qe_pin_request(struct device_node *np, int index)
{
struct qe_pin *qe_pin;
struct device_node *gc;
struct of_gpio_chip *of_gc = NULL;
struct of_mm_gpio_chip *mm_gc;
struct qe_gpio_chip *qe_gc;
int err;
int size;
const void *gpio_spec;
const u32 *gpio_cells;
unsigned long flags;
qe_pin = kzalloc(sizeof(*qe_pin), GFP_KERNEL);
if (!qe_pin) {
pr_debug("%s: can't allocate memory\n", __func__);
return ERR_PTR(-ENOMEM);
}
err = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
&gc, &gpio_spec);
if (err) {
pr_debug("%s: can't parse gpios property\n", __func__);
goto err0;
}
if (!of_device_is_compatible(gc, "fsl,mpc8323-qe-pario-bank")) {
pr_debug("%s: tried to get a non-qe pin\n", __func__);
err = -EINVAL;
goto err1;
}
of_gc = gc->data;
if (!of_gc) {
pr_debug("%s: gpio controller %s isn't registered\n",
np->full_name, gc->full_name);
err = -ENODEV;
goto err1;
}
gpio_cells = of_get_property(gc, "#gpio-cells", &size);
if (!gpio_cells || size != sizeof(*gpio_cells) ||
*gpio_cells != of_gc->gpio_cells) {
pr_debug("%s: wrong #gpio-cells for %s\n",
np->full_name, gc->full_name);
err = -EINVAL;
goto err1;
}
err = of_gc->xlate(of_gc, np, gpio_spec, NULL);
if (err < 0)
goto err1;
mm_gc = to_of_mm_gpio_chip(&of_gc->gc);
qe_gc = to_qe_gpio_chip(mm_gc);
spin_lock_irqsave(&qe_gc->lock, flags);
if (test_and_set_bit(QE_PIN_REQUESTED, &qe_gc->pin_flags[err]) == 0) {
qe_pin->controller = qe_gc;
qe_pin->num = err;
err = 0;
} else {
err = -EBUSY;
}
spin_unlock_irqrestore(&qe_gc->lock, flags);
if (!err)
return qe_pin;
err1:
of_node_put(gc);
err0:
kfree(qe_pin);
pr_debug("%s failed with status %d\n", __func__, err);
return ERR_PTR(err);
}
EXPORT_SYMBOL(qe_pin_request);
/**
* qe_pin_free - Free a pin
* @qe_pin: pointer to the qe_pin structure
* Context: any
*
* This function frees the qe_pin structure and makes a pin available
* for further qe_pin_request() calls.
*/
void qe_pin_free(struct qe_pin *qe_pin)
{
struct qe_gpio_chip *qe_gc = qe_pin->controller;
unsigned long flags;
const int pin = qe_pin->num;
spin_lock_irqsave(&qe_gc->lock, flags);
test_and_clear_bit(QE_PIN_REQUESTED, &qe_gc->pin_flags[pin]);
spin_unlock_irqrestore(&qe_gc->lock, flags);
kfree(qe_pin);
}
EXPORT_SYMBOL(qe_pin_free);
/**
* qe_pin_set_dedicated - Revert a pin to a dedicated peripheral function mode
* @qe_pin: pointer to the qe_pin structure
* Context: any
*
* This function resets a pin to a dedicated peripheral function that
* has been set up by the firmware.
*/
void qe_pin_set_dedicated(struct qe_pin *qe_pin)
{
struct qe_gpio_chip *qe_gc = qe_pin->controller;
struct qe_pio_regs __iomem *regs = qe_gc->mm_gc.regs;
struct qe_pio_regs *sregs = &qe_gc->saved_regs;
int pin = qe_pin->num;
u32 mask1 = 1 << (QE_PIO_PINS - (pin + 1));
u32 mask2 = 0x3 << (QE_PIO_PINS - (pin % (QE_PIO_PINS / 2) + 1) * 2);
bool second_reg = pin > (QE_PIO_PINS / 2) - 1;
unsigned long flags;
spin_lock_irqsave(&qe_gc->lock, flags);
if (second_reg) {
clrsetbits_be32(&regs->cpdir2, mask2, sregs->cpdir2 & mask2);
clrsetbits_be32(&regs->cppar2, mask2, sregs->cppar2 & mask2);
} else {
clrsetbits_be32(&regs->cpdir1, mask2, sregs->cpdir1 & mask2);
clrsetbits_be32(&regs->cppar1, mask2, sregs->cppar1 & mask2);
}
if (sregs->cpdata & mask1)
qe_gc->cpdata |= mask1;
else
qe_gc->cpdata &= ~mask1;
out_be32(&regs->cpdata, qe_gc->cpdata);
clrsetbits_be32(&regs->cpodr, mask1, sregs->cpodr & mask1);
spin_unlock_irqrestore(&qe_gc->lock, flags);
}
EXPORT_SYMBOL(qe_pin_set_dedicated);
/**
* qe_pin_set_gpio - Set a pin to the GPIO mode
* @qe_pin: pointer to the qe_pin structure
* Context: any
*
* This function sets a pin to the GPIO mode.
*/
void qe_pin_set_gpio(struct qe_pin *qe_pin)
{
struct qe_gpio_chip *qe_gc = qe_pin->controller;
struct qe_pio_regs __iomem *regs = qe_gc->mm_gc.regs;
unsigned long flags;
spin_lock_irqsave(&qe_gc->lock, flags);
/* Let's make it input by default, GPIO API is able to change that. */
__par_io_config_pin(regs, qe_pin->num, QE_PIO_DIR_IN, 0, 0, 0);
spin_unlock_irqrestore(&qe_gc->lock, flags);
}
EXPORT_SYMBOL(qe_pin_set_gpio);
static int __init qe_add_gpiochips(void)
{
struct device_node *np;