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Date: Wed, 31 Mar 2021 21:10:41 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Brad Larson <brad@...sando.io>
Cc: linux-arm-kernel@...ts.infradead.org, arnd@...db.de,
linus.walleij@...aro.org, bgolaszewski@...libre.com,
broonie@...nel.org, adrian.hunter@...el.com,
ulf.hansson@...aro.org, olof@...om.net, linux-gpio@...r.kernel.org,
linux-spi@...r.kernel.org, linux-mmc@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/13] gpio: Add Elba SoC gpio driver for spi cs
control
On Sun, Mar 28, 2021 at 06:59:26PM -0700, Brad Larson wrote:
> This GPIO driver is for the Pensando Elba SoC which
> provides control of four chip selects on two SPI busses.
>
> Signed-off-by: Brad Larson <brad@...sando.io>
> ---
> drivers/gpio/Kconfig | 6 ++
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-elba-spics.c | 114 +++++++++++++++++++++++++++++++++
> 3 files changed, 121 insertions(+)
> create mode 100644 drivers/gpio/gpio-elba-spics.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index e3607ec4c2e8..4720459b24f5 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -241,6 +241,12 @@ config GPIO_EIC_SPRD
> help
> Say yes here to support Spreadtrum EIC device.
>
> +config GPIO_ELBA_SPICS
> + bool "Pensando Elba SPI chip-select"
> + depends on (ARCH_PENSANDO_ELBA_SOC || COMPILE_TEST)
> + help
> + Say yes here to support the Penasndo Elba SoC SPI chip-select driver
> +
> config GPIO_EM
> tristate "Emma Mobile GPIO"
> depends on (ARCH_EMEV2 || COMPILE_TEST) && OF_GPIO
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index c58a90a3c3b1..c5c7acad371b 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_GPIO_DAVINCI) += gpio-davinci.o
> obj-$(CONFIG_GPIO_DLN2) += gpio-dln2.o
> obj-$(CONFIG_GPIO_DWAPB) += gpio-dwapb.o
> obj-$(CONFIG_GPIO_EIC_SPRD) += gpio-eic-sprd.o
> +obj-$(CONFIG_GPIO_ELBA_SPICS) += gpio-elba-spics.o
> obj-$(CONFIG_GPIO_EM) += gpio-em.o
> obj-$(CONFIG_GPIO_EP93XX) += gpio-ep93xx.o
> obj-$(CONFIG_GPIO_EXAR) += gpio-exar.o
> diff --git a/drivers/gpio/gpio-elba-spics.c b/drivers/gpio/gpio-elba-spics.c
> new file mode 100644
> index 000000000000..351bbaeea033
> --- /dev/null
> +++ b/drivers/gpio/gpio-elba-spics.c
> @@ -0,0 +1,114 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Pensando Elba SoC SPI chip select driver
> + *
> + * Copyright (c) 2020-2021, Pensando Systems Inc.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/init.h>
> +//#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +
> +/*
> + * pin: 3 2 | 1 0
> + * bit: 7------6------5------4----|---3------2------1------0
> + * cs1 cs1_ovr cs0 cs0_ovr | cs1 cs1_ovr cs0 cs0_ovr
> + * ssi1 | ssi0
> + */
> +#define SPICS_PIN_SHIFT(pin) (2 * (pin))
> +#define SPICS_MASK(pin) (0x3 << SPICS_PIN_SHIFT(pin))
> +#define SPICS_SET(pin, val) ((((val) << 1) | 0x1) << SPICS_PIN_SHIFT(pin))
> +
> +struct elba_spics_priv {
> + void __iomem *base;
> + spinlock_t lock;
> + struct gpio_chip chip;
> +};
> +
> +static int elba_spics_get_value(struct gpio_chip *chip, unsigned int pin)
> +{
> + return -ENOTSUPP;
> +}
> +
> +static void elba_spics_set_value(struct gpio_chip *chip,
> + unsigned int pin, int value)
> +{
> + struct elba_spics_priv *p = gpiochip_get_data(chip);
> + unsigned long flags;
> + u32 tmp;
> +
> + /* select chip select from register */
> + spin_lock_irqsave(&p->lock, flags);
> + tmp = readl_relaxed(p->base);
> + tmp = (tmp & ~SPICS_MASK(pin)) | SPICS_SET(pin, value);
> + writel_relaxed(tmp, p->base);
> + spin_unlock_irqrestore(&p->lock, flags);
> +}
> +
> +static int elba_spics_direction_input(struct gpio_chip *chip, unsigned int pin)
> +{
> + return -ENOTSUPP;
> +}
> +
> +static int elba_spics_direction_output(struct gpio_chip *chip,
> + unsigned int pin, int value)
> +{
> + elba_spics_set_value(chip, pin, value);
> + return 0;
> +}
> +
> +static int elba_spics_probe(struct platform_device *pdev)
> +{
> + struct elba_spics_priv *p;
> + struct resource *res;
> + int ret = 0;
> +
> + p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
> + if (!p)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + p->base = devm_ioremap_resource(&pdev->dev, res);
In accordance with the DTS-node this is just a single register
0x307c2468-0x307c24C picked from some bigger block, which most likely
belongs to something like a system controller. PCIe node has got
another register from there "0x307c2480-0x307c2484/* MS CFG_WDT */",
and some BSM device too "0x307c2080-0x307c2084". Please consider using
syscon instead of directly requesting the resource here.
-Sergey
> + if (IS_ERR(p->base))
> + return PTR_ERR(p->base);
> + spin_lock_init(&p->lock);
> + platform_set_drvdata(pdev, p);
> +
> + p->chip.ngpio = 4; /* 2 cs pins for spi0, and 2 for spi1 */
> + p->chip.base = -1;
> + p->chip.direction_input = elba_spics_direction_input;
> + p->chip.direction_output = elba_spics_direction_output;
> + p->chip.get = elba_spics_get_value;
> + p->chip.set = elba_spics_set_value;
> + p->chip.label = dev_name(&pdev->dev);
> + p->chip.parent = &pdev->dev;
> + p->chip.owner = THIS_MODULE;
> +
> + ret = devm_gpiochip_add_data(&pdev->dev, &p->chip, p);
> + if (ret)
> + dev_err(&pdev->dev, "unable to add gpio chip\n");
> + return ret;
> +}
> +
> +static const struct of_device_id elba_spics_of_match[] = {
> + { .compatible = "pensando,elba-spics" },
> + {}
> +};
> +
> +static struct platform_driver elba_spics_driver = {
> + .probe = elba_spics_probe,
> + .driver = {
> + .name = "pensando-elba-spics",
> + .of_match_table = elba_spics_of_match,
> + },
> +};
> +module_platform_driver(elba_spics_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Pensando Elba SoC SPI chip-select driver");
> --
> 2.17.1
>
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