[PATCH v4 3/5] lib: utils/gpio: Add simple FDT based GPIO framework
Anup Patel
anup at brainfault.org
Sat Jul 17 01:47:46 PDT 2021
On Tue, Jul 13, 2021 at 8:54 AM Green Wan <green.wan at sifive.com> wrote:
>
> From: Anup Patel <anup.patel at wdc.com>
>
> We add a simple FDT based GPIO framework which is built on top
> of generic GPIO library. The phandle of FDT GPIO chip DT node
> is treated as unique GPIO chip ID required by the generic GPIO
> library. The FDT based GPIO chip drivers will be probed on-demand
> from fdt_gpio_pin_get() called by the GPIO client drivers.
>
> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> Reviewed-by: Atish Patra <atish.patra at wdc.com>
Applied this patch to the riscv/opensbi repo
Thanks,
Anup
> ---
> include/sbi_utils/gpio/fdt_gpio.h | 34 ++++++++
> lib/utils/gpio/fdt_gpio.c | 132 ++++++++++++++++++++++++++++++
> lib/utils/gpio/objects.mk | 1 +
> 3 files changed, 167 insertions(+)
> create mode 100644 include/sbi_utils/gpio/fdt_gpio.h
> create mode 100644 lib/utils/gpio/fdt_gpio.c
>
> diff --git a/include/sbi_utils/gpio/fdt_gpio.h b/include/sbi_utils/gpio/fdt_gpio.h
> new file mode 100644
> index 0000000..19e1b58
> --- /dev/null
> +++ b/include/sbi_utils/gpio/fdt_gpio.h
> @@ -0,0 +1,34 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2021 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + * Anup Patel <anup.patel at wdc.com>
> + */
> +
> +#ifndef __FDT_GPIO_H__
> +#define __FDT_GPIO_H__
> +
> +#include <sbi_utils/gpio/gpio.h>
> +
> +/** FDT based GPIO driver */
> +struct fdt_gpio {
> + const struct fdt_match *match_table;
> + int (*xlate)(struct gpio_chip *chip,
> + const struct fdt_phandle_args *pargs,
> + struct gpio_pin *out_pin);
> + int (*init)(void *fdt, int nodeoff, u32 phandle,
> + const struct fdt_match *match);
> +};
> +
> +/** Get a GPIO pin using "gpios" DT property of client DT node */
> +int fdt_gpio_pin_get(void *fdt, int nodeoff, int index,
> + struct gpio_pin *out_pin);
> +
> +/** Simple xlate function to convert two GPIO FDT cells into GPIO pin */
> +int fdt_gpio_simple_xlate(struct gpio_chip *chip,
> + const struct fdt_phandle_args *pargs,
> + struct gpio_pin *out_pin);
> +
> +#endif
> diff --git a/lib/utils/gpio/fdt_gpio.c b/lib/utils/gpio/fdt_gpio.c
> new file mode 100644
> index 0000000..bff391f
> --- /dev/null
> +++ b/lib/utils/gpio/fdt_gpio.c
> @@ -0,0 +1,132 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2021 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + * Anup Patel <anup.patel at wdc.com>
> + */
> +
> +#include <libfdt.h>
> +#include <sbi/sbi_error.h>
> +#include <sbi_utils/fdt/fdt_helper.h>
> +#include <sbi_utils/gpio/fdt_gpio.h>
> +
> +static struct fdt_gpio *gpio_drivers[] = {
> +};
> +
> +static struct fdt_gpio *fdt_gpio_driver(struct gpio_chip *chip)
> +{
> + int pos;
> +
> + if (!chip)
> + return NULL;
> +
> + for (pos = 0; pos < array_size(gpio_drivers); pos++) {
> + if (chip->driver == gpio_drivers[pos])
> + return gpio_drivers[pos];
> + }
> +
> + return NULL;
> +}
> +
> +static int fdt_gpio_init(void *fdt, u32 phandle)
> +{
> + int pos, nodeoff, rc;
> + struct fdt_gpio *drv;
> + const struct fdt_match *match;
> +
> + /* Find node offset */
> + nodeoff = fdt_node_offset_by_phandle(fdt, phandle);
> + if (nodeoff < 0)
> + return nodeoff;
> +
> + /* Check "gpio-controller" property */
> + if (!fdt_getprop(fdt, nodeoff, "gpio-controller", &rc))
> + return SBI_EINVAL;
> +
> + /* Try all GPIO drivers one-by-one */
> + for (pos = 0; pos < array_size(gpio_drivers); pos++) {
> + drv = gpio_drivers[pos];
> +
> + match = fdt_match_node(fdt, nodeoff, drv->match_table);
> + if (match && drv->init) {
> + rc = drv->init(fdt, nodeoff, phandle, match);
> + if (rc == SBI_ENODEV)
> + continue;
> + if (rc)
> + return rc;
> + return 0;
> + }
> + }
> +
> + return SBI_ENOSYS;
> +}
> +
> +static int fdt_gpio_chip_find(void *fdt, u32 phandle,
> + struct gpio_chip **out_chip)
> +{
> + int rc;
> + struct gpio_chip *chip = gpio_chip_find(phandle);
> +
> + if (!chip) {
> + /* GPIO chip not found so initialize matching driver */
> + rc = fdt_gpio_init(fdt, phandle);
> + if (rc)
> + return rc;
> +
> + /* Try to find GPIO chip again */
> + chip = gpio_chip_find(phandle);
> + if (!chip)
> + return SBI_ENOSYS;
> + }
> +
> + if (out_chip)
> + *out_chip = chip;
> +
> + return 0;
> +}
> +
> +int fdt_gpio_pin_get(void *fdt, int nodeoff, int index,
> + struct gpio_pin *out_pin)
> +{
> + int rc;
> + u32 phandle;
> + struct fdt_gpio *drv;
> + struct gpio_chip *chip = NULL;
> + struct fdt_phandle_args pargs;
> +
> + if (!fdt || (nodeoff < 0) || (index < 0) || !out_pin)
> + return SBI_EINVAL;
> +
> + pargs.node_offset = pargs.args_count = 0;
> + rc = fdt_parse_phandle_with_args(fdt, nodeoff,
> + "gpios", "#gpio-cells",
> + index, &pargs);
> + if (rc)
> + return rc;
> +
> + phandle = fdt_get_phandle(fdt, pargs.node_offset);
> + rc = fdt_gpio_chip_find(fdt, phandle, &chip);
> + if (rc)
> + return rc;
> +
> + drv = fdt_gpio_driver(chip);
> + if (!drv || !drv->xlate)
> + return SBI_ENOSYS;
> +
> + return drv->xlate(chip, &pargs, out_pin);
> +}
> +
> +int fdt_gpio_simple_xlate(struct gpio_chip *chip,
> + const struct fdt_phandle_args *pargs,
> + struct gpio_pin *out_pin)
> +{
> + if ((pargs->args_count < 2) || (chip->ngpio <= pargs->args[0]))
> + return SBI_EINVAL;
> +
> + out_pin->chip = chip;
> + out_pin->offset = pargs->args[0];
> + out_pin->flags = pargs->args[1];
> + return 0;
> +}
> diff --git a/lib/utils/gpio/objects.mk b/lib/utils/gpio/objects.mk
> index e99a895..dade45e 100644
> --- a/lib/utils/gpio/objects.mk
> +++ b/lib/utils/gpio/objects.mk
> @@ -7,4 +7,5 @@
> # Anup Patel <anup.patel at wdc.com>
> #
>
> +libsbiutils-objs-y += gpio/fdt_gpio.o
> libsbiutils-objs-y += gpio/gpio.o
> --
> 2.17.1
>
>
> --
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