[U-Boot] [PATCH v2] gpio: mscc-bitbang-spi: Add a simple gpio driver for bitbgang spi

[Gregory CLEMENT]

Hi,
 
 On mar., oct. 09 2018, Gregory CLEMENT <gregory.clement at bootlin.com> wrote:

> The VCore III SoCs such as the Luton but also the Ocelot can remap an SPI
> flash directly in memory. However, for writing in the flash the
> communication has to be done by software.
>
> Each of the signal used for the SPI are exposed in a single register. In
> order to be able to use the soft-spi driver, the management of this pin
> is done through this simple gpio driver.
>
> Even if the main purpose of this driver is to be used by soft-spi, it can
> still be used as a normal gpio driver but with limitation: for example
> the first pin can't be used as output.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement at bootlin.com>
> ---
> Changelog:
> v1 -> v2:
>  - use const and static when needed
>  - fix style
>  - use dev_remap_addr

I sent this version 2 months ago and addressed all the comments, how
could we going further ?

Thanks,

Gregory


>
>  drivers/gpio/Kconfig                 |   7 ++
>  drivers/gpio/Makefile                |   1 +
>  drivers/gpio/gpio-mscc-bitbang-spi.c | 122 +++++++++++++++++++++++++++
>  3 files changed, 130 insertions(+)
>  create mode 100644 drivers/gpio/gpio-mscc-bitbang-spi.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 5cd8b34400..947a59cce3 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -99,6 +99,13 @@ config LPC32XX_GPIO
>  	help
>  	  Support for the LPC32XX GPIO driver.
>  
> +config MSCC_BITBANG_SPI_GPIO
> +	bool "Microsemi bitbang spi GPIO driver"
> +	depends on DM_GPIO && SOC_VCOREIII
> +	help
> +	  Support controlling the GPIO used for SPI bitbang by software. Can
> +	  be used by the VCoreIII SoCs, but it was mainly useful for Luton.
> +
>  config MSM_GPIO
>  	bool "Qualcomm GPIO driver"
>  	depends on DM_GPIO
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index f186120684..2085dd3cba 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -58,3 +58,4 @@ obj-$(CONFIG_MVEBU_GPIO)	+= mvebu_gpio.o
>  obj-$(CONFIG_MSM_GPIO)		+= msm_gpio.o
>  obj-$(CONFIG_$(SPL_)PCF8575_GPIO)	+= pcf8575_gpio.o
>  obj-$(CONFIG_PM8916_GPIO)	+= pm8916_gpio.o
> +obj-$(CONFIG_MSCC_BITBANG_SPI_GPIO)	+= gpio-mscc-bitbang-spi.o
> diff --git a/drivers/gpio/gpio-mscc-bitbang-spi.c b/drivers/gpio/gpio-mscc-bitbang-spi.c
> new file mode 100644
> index 0000000000..b675f9052c
> --- /dev/null
> +++ b/drivers/gpio/gpio-mscc-bitbang-spi.c
> @@ -0,0 +1,122 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Microsemi SoCs pinctrl driver
> + *
> + * Author: <gregory.clement at bootlin.com>
> + * License: Dual MIT/GPL
> + * Copyright (c) 2018 Microsemi Corporation
> + */
> +
> +#include <common.h>
> +#include <asm-generic/gpio.h>
> +#include <asm/io.h>
> +#include <dm.h>
> +#include <errno.h>
> +
> +enum {
> +	SDI,
> +	CS0,
> +	CS1,
> +	CS2,
> +	CS3,
> +	SDO,
> +	SCK
> +};
> +
> +static const int pinmap[] = { 0, 5, 6, 7, 8, 10, 12 };
> +
> +#define SW_SPI_CSn_OE	 0x1E	/* bits 1 to 4 */
> +#define SW_SPI_CS0_OE	 BIT(1)
> +#define SW_SPI_SDO_OE	 BIT(9)
> +#define SW_SPI_SCK_OE	 BIT(11)
> +#define SW_PIN_CTRL_MODE BIT(13)
> +
> +struct mscc_bb_spi_gpio {
> +	void __iomem *regs;
> +	u32 cache_val;
> +};
> +
> +static int mscc_bb_spi_gpio_set(struct udevice *dev, unsigned oft, int val)
> +{
> +	struct mscc_bb_spi_gpio *gpio = dev_get_priv(dev);
> +
> +	if (val)
> +		gpio->cache_val |= BIT(pinmap[oft]);
> +	else
> +		gpio->cache_val &= ~BIT(pinmap[oft]);
> +
> +	writel(gpio->cache_val, gpio->regs);
> +
> +	return 0;
> +}
> +
> +static int mscc_bb_spi_gpio_direction_output(struct udevice *dev, unsigned oft,
> +					     int val)
> +{
> +	if (oft == 0) {
> +		pr_err("SW_SPI_DSI can't be used as output\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	mscc_bb_spi_gpio_set(dev, oft, val);
> +
> +	return 0;
> +}
> +
> +static int mscc_bb_spi_gpio_direction_input(struct udevice *dev, unsigned oft)
> +{
> +	return 0;
> +}
> +
> +static int mscc_bb_spi_gpio_get(struct udevice *dev, unsigned int oft)
> +{
> +	struct mscc_bb_spi_gpio *gpio = dev_get_priv(dev);
> +	u32 val = readl(gpio->regs);
> +
> +	return !!(val & BIT(pinmap[oft]));
> +}
> +
> +static const struct dm_gpio_ops mscc_bb_spi_gpio_ops = {
> +	.direction_output	= mscc_bb_spi_gpio_direction_output,
> +	.direction_input	= mscc_bb_spi_gpio_direction_input,
> +	.set_value		= mscc_bb_spi_gpio_set,
> +	.get_value		= mscc_bb_spi_gpio_get,
> +};
> +
> +static int mscc_bb_spi_gpio_probe(struct udevice *dev)
> +{
> +	struct mscc_bb_spi_gpio *gpio = dev_get_priv(dev);
> +	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> +
> +	gpio->regs = dev_remap_addr(dev);
> +	if (!gpio->regs)
> +		return -EINVAL;
> +
> +	uc_priv->bank_name = dev->name;
> +	uc_priv->gpio_count = ARRAY_SIZE(pinmap);
> +	/*
> +	 * Enable software mode to control the SPI pin, enables the
> +	 * output mode for most of the pin and initialize the cache
> +	 * value in the same time
> +	 */
> +
> +	gpio->cache_val = SW_PIN_CTRL_MODE | SW_SPI_SCK_OE | SW_SPI_SDO_OE |
> +	    SW_SPI_CS0_OE;
> +	writel(gpio->cache_val, gpio->regs);
> +
> +	return 0;
> +}
> +
> +static const struct udevice_id mscc_bb_spi_gpio_ids[] = {
> +	{.compatible = "mscc,spi-bitbang-gpio"},
> +	{}
> +};
> +
> +U_BOOT_DRIVER(gpio_mscc_bb_spi) = {
> +	.name	= "gpio-mscc-spi-bitbang",
> +	.id	= UCLASS_GPIO,
> +	.ops	= &mscc_bb_spi_gpio_ops,
> +	.probe	= mscc_bb_spi_gpio_probe,
> +	.of_match = of_match_ptr(mscc_bb_spi_gpio_ids),
> +	.priv_auto_alloc_size = sizeof(struct mscc_bb_spi_gpio),
> +};
> -- 
> 2.19.1
>

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com