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Date: Tue, 3 Feb 2015 14:21:43 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Chao Xie <chao.xie@...vell.com>
Cc: Alexandre Courbot <gnurou@...il.com>,
"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
xiechao_mail@....com, Haojian Zhuang <haojian.zhuang@...il.com>
Subject: Re: [PATCH] gpio: mmp: add GPIO driver for Marvell MMP series
On Wed, Jan 28, 2015 at 3:30 AM, Chao Xie <chao.xie@...vell.com> wrote:
> From: Chao Xie <chao.xie@...vell.com>
>
> For some old PXA series, they used PXA GPIO driver.
> The IP of GPIO changes since PXA988 which is Marvell MMP
> series.
> It will use new way to control the GPIO level, direction
> and edge status.
>
> Signed-off-by: Chao Xie <chao.xie@...vell.com>
(...)
> +config GPIO_MMP
> + bool "MMP GPIO support"
> + depends on ARCH_MMP
All new simple drivers with IRQ should
select GPIOLIB_IRQCHIP
Since this looks like a basic MMIO driver I think
you should also use:
select GPIO_GENERIC
And set up simple getter/setter functions with a
> + help
> + Say yes here to support the MMP GPIO device at PXA1088/PXA1908/PXA1928.
> + Comparing with PXA GPIO device, the IP of MMP GPIO changes a lot.
> +
(...)
> +++ b/drivers/gpio/gpio-mmp.c
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/irq.h>
You don't need this include with GPIOLIB_IRQCHIP
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/gpio.h>
#include <linux/gpio/driver.h>
> +#include <linux/clk.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/irqdomain.h>
> +#include <linux/irqchip/chained_irq.h>
get rid of these two includes in favor of using GPIOLIB_IRQCHIP
> +#include <linux/platform_data/gpio-mmp.h>
Add:
#include <linux/basic_mmio_gpio.h>
And implement generic GPIO using bgpio_init()
(...)
> +#define GPLR 0x0
> +#define GPDR 0xc
> +#define GPSR 0x18
> +#define GPCR 0x24
> +#define GRER 0x30
> +#define GFER 0x3c
> +#define GEDR 0x48
> +#define GSDR 0x54
> +#define GCDR 0x60
> +#define GSRER 0x6c
> +#define GCRER 0x78
> +#define GSFER 0x84
> +#define GCFER 0x90
> +#define GAPMASK 0x9c
> +#define GCPMASK 0xa8
> +
> +/* Bank will have 2^n GPIOes, and for mmp-gpio n = 5 */
> +#define BANK_GPIO_ORDER 5
> +#define BANK_GPIO_NUMBER (1 << BANK_GPIO_ORDER)
> +#define BANK_GPIO_MASK (BANK_GPIO_NUMBER - 1)
> +
> +#define mmp_gpio_to_bank_idx(gpio) ((gpio) >> BANK_GPIO_ORDER)
> +#define mmp_gpio_to_bank_offset(gpio) ((gpio) & BANK_GPIO_MASK)
> +#define mmp_bank_to_gpio(idx, offset) (((idx) << BANK_GPIO_ORDER) \
> + | ((offset) & BANK_GPIO_MASK))
> +
This looks convoluted. Why not just register each bank as a separate
device instead of trying to figure out bank index like this?
> +struct mmp_gpio_bank {
> + void __iomem *reg_bank;
> + u32 irq_mask;
> + u32 irq_rising_edge;
> + u32 irq_falling_edge;
> +};
> +
> +struct mmp_gpio_chip {
> + struct gpio_chip chip;
That should then be
struct bgpio_chip bgc;
For generic GPIO.
> + void __iomem *reg_base;
> + int irq;
> + struct irq_domain *domain;
These two will not be necessary to keep around with
GPIOLIB_IRQCHIP
> + unsigned int ngpio;
This is part of struct gpio_chip so do not duplicate it.
> + unsigned int nbank;
> + struct mmp_gpio_bank *banks;
And those two I think you should get rid of by creating one
chip per bank.
> +};
So merge these two into one struct and instantiate one device for
each bank.
> +static int mmp_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
> +{
> + struct mmp_gpio_chip *mmp_chip =
> + container_of(chip, struct mmp_gpio_chip, chip);
> +
> + return irq_create_mapping(mmp_chip->domain, offset);
> +}
This function goes away with GPIOLIB_IRQCHIP.
Just leave it unassigned and let the core handle this translation.
> +static int mmp_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> +{
> + struct mmp_gpio_chip *mmp_chip =
> + container_of(chip, struct mmp_gpio_chip, chip);
Create a static inline to cast the gpio_chip to a mmp_chip like
this:
static inline struct mmp_gpio_chip *to_mmp(struct gpio_chip *gc)
{
return container_of(chip, struct mmp_gpio_chip, chip);
}
Use that everywhere to simplify.
> + struct mmp_gpio_bank *bank =
> + &mmp_chip->banks[mmp_gpio_to_bank_idx(offset)];
> + u32 bit = (1 << mmp_gpio_to_bank_offset(offset));
And get rid of this by using one device per bank.
> +static int mmp_gpio_direction_output(struct gpio_chip *chip,
> +static int mmp_gpio_get(struct gpio_chip *chip, unsigned offset)
> +static void mmp_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
Looks like generic GPIO will do the job.
> +#ifdef CONFIG_OF_GPIO
> +static int mmp_gpio_of_xlate(struct gpio_chip *chip,
> + const struct of_phandle_args *gpiospec,
> + u32 *flags)
> +{
> + struct mmp_gpio_chip *mmp_chip =
> + container_of(chip, struct mmp_gpio_chip, chip);
> +
> + /* GPIO index start from 0. */
> + if (gpiospec->args[0] >= mmp_chip->ngpio)
> + return -EINVAL;
> +
> + if (flags)
> + *flags = gpiospec->args[1];
> +
> + return gpiospec->args[0];
> +}
> +#endif
This also goes to the generic xlate with one device per bank.
> +static int mmp_gpio_irq_type(struct irq_data *d, unsigned int type)
> +static void mmp_gpio_demux_handler(unsigned int irq, struct irq_desc *desc)
> +static void mmp_ack_muxed_gpio(struct irq_data *d)
> +static void mmp_mask_muxed_gpio(struct irq_data *d)
> +static void mmp_unmask_muxed_gpio(struct irq_data *d)
Looks OK but make sure to convert to GPIOLIB_IRQCHIP and convert from
struct gpio_chip * passed as irq_data *d to the internal chip type
with the new to_mmp().
(...)
>From here:
> +static int mmp_irq_domain_map(struct irq_domain *d, unsigned int irq,
> + irq_hw_number_t hw)
> +{
> + irq_set_chip_and_handler(irq, &mmp_muxed_gpio_chip,
> + handle_edge_irq);
> + irq_set_chip_data(irq, d->host_data);
> + set_irq_flags(irq, IRQ_TYPE_NONE);
> +
> + return 0;
> +}
> +
> +static const struct irq_domain_ops mmp_gpio_irq_domain_ops = {
> + .map = mmp_irq_domain_map,
> + .xlate = irq_domain_xlate_twocell,
> +};
To here goes away with GPIOLIB_IRQCHIP (moved to core).
> +#ifdef CONFIG_OF_GPIO
> + mmp_chip->chip.of_node = np;
> + mmp_chip->chip.of_xlate = mmp_gpio_of_xlate;
> + mmp_chip->chip.of_gpio_n_cells = 2;
> +#endif
Can't we just select or depend on OF_GPIO for this
driver and get rid of the #fidef:s?
> +static int __init mmp_gpio_init(void)
> +{
> + return platform_driver_register(&mmp_gpio_driver);
> +}
> +postcore_initcall(mmp_gpio_init);
Why does this nees to be postcore? A normal module
would be nice.
Yours,
Linus Walleij
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