Devices sharing a reset GPIO could use the reset framework for coordinated handling of that shared GPIO line. We have several cases of such needs, at least for Devicetree-based platforms.

If Devicetree-based device requests a reset line which is missing but there is a reset-gpios property, instantiate a new "reset-gpio" platform device which will handle such reset line. This allows seamless handling of such shared reset-gpios without need of changing Devicetree binding [1].

The "reset-gpio" driver follows shortly.

Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@robh.at.kernel.org/ Cc: Bartosz Golaszewski brgl@bgdev.pl Cc: Sean Anderson sean.anderson@seco.com Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org --- drivers/reset/core.c | 70 +++++++++++++++++++++++++++----- include/linux/reset-controller.h | 2 + 2 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c index 4d5a78d3c085..a1f0f515a7e0 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -10,9 +10,12 @@ #include <linux/export.h> #include <linux/kernel.h> #include <linux/kref.h> +#include <linux/gpio/consumer.h> #include <linux/module.h> #include <linux/of.h> +#include <linux/of_gpio.h> #include <linux/acpi.h> +#include <linux/platform_device.h> #include <linux/reset.h> #include <linux/reset-controller.h> #include <linux/slab.h> @@ -813,13 +816,59 @@ static void __reset_control_put_internal(struct reset_control *rstc) kref_put(&rstc->refcnt, __reset_control_release); }

+static int __reset_add_reset_gpio_device(struct device_node *node, + const struct gpio_desc **out) +{ + struct platform_device *pdev; + int gpio; + + /* Don't care about deprecated '-gpio' suffix. */ + gpio = of_get_named_gpio(node, "reset-gpios", 0); + if (!gpio_is_valid(gpio)) + return gpio; + + pdev = platform_device_register_data(NULL, "reset-gpio", + PLATFORM_DEVID_AUTO, &node, + sizeof(node)); + if (!IS_ERR(pdev)) + *out = gpio_to_desc(gpio); + + return PTR_ERR_OR_ZERO(pdev); +} + +static struct reset_controller_dev *__reset_find_rcdev(const struct of_phandle_args *args, + const void *cookie) +{ + struct reset_controller_dev *r, *rcdev; + + lockdep_assert_held(&reset_list_mutex); + + rcdev = NULL; + list_for_each_entry(r, &reset_controller_list, list) { + if (args && args->np) { + if (args->np == r->of_node) { + rcdev = r; + break; + } + } else if (cookie) { + if (cookie == r->cookie) { + rcdev = r; + break; + } + } + } + + return rcdev; +} + struct reset_control * __of_reset_control_get(struct device_node *node, const char *id, int index, bool shared, bool optional, bool acquired) { + const struct gpio_desc *gpio = NULL; + struct of_phandle_args args = {0}; struct reset_control *rstc; - struct reset_controller_dev *r, *rcdev; - struct of_phandle_args args; + struct reset_controller_dev *rcdev; int rstc_id; int ret;

@@ -839,17 +888,16 @@ __of_reset_control_get(struct device_node *node, const char *id, int index, index, &args); if (ret == -EINVAL) return ERR_PTR(ret); - if (ret) - return optional ? NULL : ERR_PTR(ret); + if (ret) { + ret = __reset_add_reset_gpio_device(node, &gpio); + if (ret) + return optional ? NULL : ERR_PTR(ret); + + args.args_count = 1; /* reset-gpio has only one reset line */ + }

mutex_lock(&reset_list_mutex); - rcdev = NULL; - list_for_each_entry(r, &reset_controller_list, list) { - if (args.np == r->of_node) { - rcdev = r; - break; - } - } + rcdev = __reset_find_rcdev(&args, gpio);

if (!rcdev) { rstc = ERR_PTR(-EPROBE_DEFER); diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h index 0fa4f60e1186..c0a99a8ea29e 100644 --- a/include/linux/reset-controller.h +++ b/include/linux/reset-controller.h @@ -61,6 +61,7 @@ struct reset_control_lookup { * @dev: corresponding driver model device struct * @of_node: corresponding device tree node as phandle target * @of_reset_n_cells: number of cells in reset line specifiers + * @cookie: for reset-gpios controllers: corresponding GPIO instead of of_node * @of_xlate: translation function to translate from specifier as found in the * device tree to id as given to the reset control ops, defaults * to :c:func:`of_reset_simple_xlate`. @@ -74,6 +75,7 @@ struct reset_controller_dev { struct device *dev; struct device_node *of_node; int of_reset_n_cells; + const void *cookie; int (*of_xlate)(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec); unsigned int nr_resets;

Add simple driver to control GPIO-based resets using the reset controller API for the cases when the GPIOs are shared and reset should be coordinated. The driver is expected to be used by reset core framework for ad-hoc reset controllers.

Cc: Bartosz Golaszewski brgl@bgdev.pl Cc: Sean Anderson sean.anderson@seco.com Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org --- MAINTAINERS | 5 ++ drivers/reset/Kconfig | 9 ++++ drivers/reset/Makefile | 1 + drivers/reset/reset-gpio.c | 105 +++++++++++++++++++++++++++++++++++++ 4 files changed, 120 insertions(+) create mode 100644 drivers/reset/reset-gpio.c

diff --git a/MAINTAINERS b/MAINTAINERS index 7fe27cd60e1b..a0fbd4814bc7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8866,6 +8866,11 @@ F: Documentation/i2c/muxes/i2c-mux-gpio.rst F: drivers/i2c/muxes/i2c-mux-gpio.c F: include/linux/platform_data/i2c-mux-gpio.h

+GENERIC GPIO RESET DRIVER +M: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org +S: Maintained +F: drivers/reset/reset-gpio.c + GENERIC HDLC (WAN) DRIVERS M: Krzysztof Halasa khc@pm.waw.pl S: Maintained diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index ccd59ddd7610..bb1b5a326eb7 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1 on BCM7216.

+config RESET_GPIO + tristate "GPIO reset controller" + help + This enables a generic reset controller for resets attached via + GPIOs. Typically for OF platforms this driver expects "reset-gpios" + property. + + If compiled as module, it will be called reset-gpio. + config RESET_HSDK bool "Synopsys HSDK Reset Driver" depends on HAS_IOMEM diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 8270da8a4baa..fd8b49fa46fc 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o +obj-$(CONFIG_RESET_GPIO) += reset-gpio.o obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o obj-$(CONFIG_RESET_IMX7) += reset-imx7.o obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o diff --git a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c new file mode 100644 index 000000000000..6952996dbc9f --- /dev/null +++ b/drivers/reset/reset-gpio.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/gpio/consumer.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> + +struct reset_gpio_priv { + struct reset_controller_dev rc; + struct gpio_desc *reset; +}; + +static inline struct reset_gpio_priv +*rc_to_reset_gpio(struct reset_controller_dev *rc) +{ + return container_of(rc, struct reset_gpio_priv, rc); +} + +static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned long id) +{ + struct reset_gpio_priv *priv = rc_to_reset_gpio(rc); + + gpiod_set_value_cansleep(priv->reset, 1); + + return 0; +} + +static int reset_gpio_deassert(struct reset_controller_dev *rc, + unsigned long id) +{ + struct reset_gpio_priv *priv = rc_to_reset_gpio(rc); + + gpiod_set_value_cansleep(priv->reset, 0); + + return 0; +} + +static int reset_gpio_status(struct reset_controller_dev *rc, unsigned long id) +{ + struct reset_gpio_priv *priv = rc_to_reset_gpio(rc); + + return gpiod_get_value_cansleep(priv->reset); +} + +static const struct reset_control_ops reset_gpio_ops = { + .assert = reset_gpio_assert, + .deassert = reset_gpio_deassert, + .status = reset_gpio_status, +}; + +static int reset_gpio_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct device_node **platdata = dev_get_platdata(dev); + struct reset_gpio_priv *priv; + + if (!platdata && !*platdata) + return -EINVAL; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, &priv->rc); + device_set_node(dev, of_fwnode_handle(*platdata)); + + /* + * Need to get non-exclusive because it is used in reset core as cookie + * to find existing controllers. However the actual use is exclusive. + */ + priv->reset = devm_gpiod_get(dev, "reset", + GPIOD_OUT_HIGH); + if (IS_ERR(priv->reset)) + return dev_err_probe(dev, PTR_ERR(priv->reset), + "Could not get reset gpios\n"); + + priv->rc.ops = &reset_gpio_ops; + priv->rc.owner = THIS_MODULE; + priv->rc.dev = dev; + priv->rc.cookie = priv->reset; + priv->rc.nr_resets = 1; + + return devm_reset_controller_register(dev, &priv->rc); +} + +static const struct platform_device_id reset_gpio_ids[] = { + { .name = "reset-gpio", }, + {} +}; +MODULE_DEVICE_TABLE(platform, reset_gpio_ids); + +static struct platform_driver reset_gpio_driver = { + .probe = reset_gpio_probe, + .id_table = reset_gpio_ids, + .driver = { + .name = "reset-gpio", + }, +}; +module_platform_driver(reset_gpio_driver); + +MODULE_AUTHOR("Krzysztof Kozlowski krzysztof.kozlowski@linaro.org"); +MODULE_DESCRIPTION("Generic GPIO reset driver"); +MODULE_LICENSE("GPL");

On newer Qualcomm platforms, like X1E80100-CRD, the WSA884x speakers share SD_N GPIOs between two speakers, thus a coordinated assertion is needed. Linux supports handling shared GPIO lines through "reset-gpios" property, thus allow specifying either powerdown or reset GPIOs (these are the same).

Cc: Bartosz Golaszewski brgl@bgdev.pl Cc: Sean Anderson sean.anderson@seco.com Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org

---

If previous patches are fine, then this commit is independent and could be taken via ASoC. --- .../devicetree/bindings/sound/qcom,wsa8840.yaml | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/sound/qcom,wsa8840.yaml b/Documentation/devicetree/bindings/sound/qcom,wsa8840.yaml index d717017b0fdb..4b4bcbeba9c1 100644 --- a/Documentation/devicetree/bindings/sound/qcom,wsa8840.yaml +++ b/Documentation/devicetree/bindings/sound/qcom,wsa8840.yaml @@ -28,6 +28,10 @@ properties: description: Powerdown/Shutdown line to use (pin SD_N) maxItems: 1

+ reset-gpios: + description: Powerdown/Shutdown line to use (pin SD_N) + maxItems: 1 + '#sound-dai-cells': const: 0

@@ -37,11 +41,14 @@ properties: required: - compatible - reg - - powerdown-gpios - '#sound-dai-cells' - vdd-1p8-supply - vdd-io-supply

+oneOf: + - powerdown-gpios + - reset-gpios + unevaluatedProperties: false

examples: