Re: [PATCH v2] gpio: keystone: add dsp gpio controller driver

[Suman Anna <s-anna@ti.com>]

Grygorii,

On 07/23/2014 09:44 AM, Strashko, Grygorii wrote:
> From: Murali Karicheri <m-karicheri2@ti.com>
> 
> On Keystone SOCs, ARM host can send interrupts to DSP cores using the
> DSP GPIO controller IP. Each DSP GPIO controller provides 28 IRQ signals for
> each DSP core. This is one of the component used by the IPC mechanism used
> on Keystone SOCs.
> 
> Keystone 2 DSP GPIO controller has specific features:
> - each GPIO can be configured only as output pin;
> - setting GPIO value to 1 causes IRQ generation on target DSP core;
> - reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still
>   pending.
> 
> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> ---
> Changes in v2:
> - minor comments applied
> 
> v1:
>  https://lkml.org/lkml/2014/7/16/170
> 
>  .../devicetree/bindings/gpio/gpio-keystone.txt     |   43 ++++++
>  drivers/gpio/Kconfig                               |    8 ++
>  drivers/gpio/Makefile                              |    1 +
>  drivers/gpio/gpio-keystone.c                       |  138 ++++++++++++++++++++
>  4 files changed, 190 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-keystone.txt
>  create mode 100644 drivers/gpio/gpio-keystone.c
> 
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-keystone.txt b/Documentation/devicetree/bindings/gpio/gpio-keystone.txt
> new file mode 100644
> index 0000000..d412711
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/gpio-keystone.txt
> @@ -0,0 +1,43 @@
> +Keystone 2 DSP GPIO controller bindings
> +
> +HOST OS userland running on ARM can send interrupts to DSP cores using
> +the DSP GPIO controller IP. It provides 28 IRQ signals per each DSP core.
> +This is one of the component used by the IPC mechanism used on Keystone SOCs.
> +
> +For example TCI6638K2K SoC has 8 DSP GPIO controllers:
> + - 8 for C66x CorePacx CPUs 0-7
> +
> +Keystone 2 DSP GPIO controller has specific features:
> +- each GPIO can be configured only as output pin;
> +- setting GPIO value to 1 causes IRQ generation on target DSP core;
> +- reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still
> +  pending.
> +
> +Required Properties:
> +- compatible: should be "ti,keystone-dsp-gpio"
> +
> +- ti,syscon-dev : phandle/offset pair. The phandle to syscon used to
> +				  access device state control registers and the offset
> +				  in order to use block of device's specific registers.
> +
> +- gpio-controller : Marks the device node as a gpio controller.
> +
> +- #gpio-cells : Should be one.
> +				See gpio.txt in this directory for a of the cells format
> +
> +Please refer to gpio.txt in this directory for details of the common GPIO
> +bindings used by client devices.
> +
> +Example:
> +	dspgpio0: keystone_dsp_gpio@02620240 {
> +		compatible = "ti,keystone-dsp-gpio";
> +		ti,syscon-dev = <&devctrl 0x240>;
> +		gpio-controller;
> +		#gpio-cells = <2>;

Mismatch? Conflicts with "Should be one".

> +	};
> +
> +	dsp0: dsp0 {
> +		compatible = "linux,rproc-user";
> +		...
> +		kick-gpio = <&dspgpio0 27>;
> +	};
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 4a1b511..990871f 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -158,6 +158,14 @@ config GPIO_EP93XX
>  	depends on ARCH_EP93XX
>  	select GPIO_GENERIC
>  
> +config GPIO_KEYSTONE_DSP
> +	tristate "Keystone DSP GPIO support"
> +	depends on ARCH_KEYSTONE
> +	help
> +	  Say yes here to support the DSP GPIO driver for Keystone 2. This defines
> +	  up to 28 GPIOs per each Remote (DSP) core. This is used to send
> +	  signals from ARM to the Remote (DSP) core.
> +
>  config GPIO_ZEVIO
>  	bool "LSI ZEVIO SoC memory mapped GPIOs"
>  	depends on ARM && OF_GPIO
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index d10f6a9..15c3389 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_GPIO_IOP)		+= gpio-iop.o
>  obj-$(CONFIG_GPIO_IT8761E)	+= gpio-it8761e.o
>  obj-$(CONFIG_GPIO_JANZ_TTL)	+= gpio-janz-ttl.o
>  obj-$(CONFIG_GPIO_KEMPLD)	+= gpio-kempld.o
> +obj-$(CONFIG_GPIO_KEYSTONE_DSP)	+= gpio-keystone.o
>  obj-$(CONFIG_ARCH_KS8695)	+= gpio-ks8695.o
>  obj-$(CONFIG_GPIO_INTEL_MID)	+= gpio-intel-mid.o
>  obj-$(CONFIG_GPIO_LP3943)	+= gpio-lp3943.o
> diff --git a/drivers/gpio/gpio-keystone.c b/drivers/gpio/gpio-keystone.c
> new file mode 100644
> index 0000000..7909a1c
> --- /dev/null
> +++ b/drivers/gpio/gpio-keystone.c
> @@ -0,0 +1,138 @@
> +/*
> + * Keystone 2 DSP GPIO support.
> + *
> + * Copyright (C) 2014 Texas Instruments, Inc.
> + * Author: Murali Karicheri <m-karicheri2@ti.com>
> + *	   Grygorii Strashko <grygorii.strashko@ti.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/gpio.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +
> +/* 28 bits in IPCGRx are treated as GPIO pins to generate interrupt */
> +#define GPIOS_PER_BANK		28
> +#define GPIO_OFFSET		4
> +
> +struct keystone_gpio_bank {
> +	struct gpio_chip	 chip;
> +	struct device		*dev;
> +	struct regmap		*devctrl_regs;
> +	u32			devctrl_offset;
> +};
> +#define chip_to_bank(c) \
> +	container_of(c, struct keystone_gpio_bank, chip)
> +
> +static int keystone_gpio_direction_out(struct gpio_chip *c,
> +					unsigned ofs, int val)
> +{
> +	return 0;
> +}
> +
> +static int keystone_gpio_get(struct gpio_chip *c, unsigned ofs)
> +{
> +	struct keystone_gpio_bank *bank = chip_to_bank(c);
> +	int bit = ofs + GPIO_OFFSET;
> +	int ret;
> +	u32 val = 0;
> +
> +	ret = regmap_read(bank->devctrl_regs, bank->devctrl_offset, &val);
> +	if (ret < 0)
> +		dev_dbg(bank->dev, "gpio read failed ret(%d)\n", ret);
> +
> +	return (val >> bit) & 1;
> +}
> +
> +static void keystone_gpio_set(struct gpio_chip *c, unsigned ofs, int val)
> +{
> +	struct keystone_gpio_bank *bank = chip_to_bank(c);
> +	int bit = ofs + GPIO_OFFSET;
> +	int ret;
> +
> +	if (!val)
> +		return;
> +
> +	ret = regmap_write(bank->devctrl_regs, bank->devctrl_offset,
> +			   BIT(bit) | 1);

What is this ORing with 1 for?

regards
Suman

[snip]