| Message ID | 20220125124930.50369-2-yangyicong@hisilicon.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add I2C bus recovery support on Kunpeng 920/930 | expand |
On Mon, Feb 07, 2022 at 01:17:49PM +0200, Andy Shevchenko wrote: > On Tue, Jan 25, 2022 at 08:49:29PM +0800, Yicong Yang wrote: > > Add generic GPIO bus recovery support for i2c-hisi driver > > by registering the recovery information with core provided > > i2c_generic_scl_recovery() method. > > > > As the SCL/SDA pins are multiplexed with GPIO, we need to > > switch the pins mux to GPIO before recovery and switch back > > after recovery. It's implemented by the ACPI method in > > the i2c_bus_recovery_info->{prepare,unprepare}_recovery() > > method. > > NAK. > > ACPI has its own resources for that. What is missed is the layer between ACPI > and pin control. To be more precise, https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinconfig-pin-configuration-descriptor-macro https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinfunction-pin-function-descriptor-macro https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroup-pin-group-descriptor-macro https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroupconfig-pin-group-configuration-descriptor-macro
[ +cc pinctrl list for visible ] Hi Andy, Thanks for the reply. On 2022/2/7 19:20, Andy Shevchenko wrote: > On Mon, Feb 07, 2022 at 01:17:49PM +0200, Andy Shevchenko wrote: >> On Tue, Jan 25, 2022 at 08:49:29PM +0800, Yicong Yang wrote: >>> Add generic GPIO bus recovery support for i2c-hisi driver >>> by registering the recovery information with core provided >>> i2c_generic_scl_recovery() method. >>> >>> As the SCL/SDA pins are multiplexed with GPIO, we need to >>> switch the pins mux to GPIO before recovery and switch back >>> after recovery. It's implemented by the ACPI method in >>> the i2c_bus_recovery_info->{prepare,unprepare}_recovery() >>> method. >> >> NAK. >> >> ACPI has its own resources for that. What is missed is the layer between ACPI >> and pin control. > I think that's where the problem is and why we use this approach. When I looked into devm_pinctrl_get(), it stops when fails to retrieve the pin info from device tree. So I cannot use it on our ACPI server for the pinmux. I looked into the history that Irina raised an RFC for adding the ACPI support in pinctrl[1], but at that time seems it lacks some standard support. But maybe now we can support it? But based on the current situation maybe the implementation of this patch suits best. And currently we don't have a pinctrl driver for doing the multiplexing (though I think it's easy to add one but maybe only configures 2 pins for now). [1] https://lore.kernel.org/all/CACRpkdbj==q5wp2Z5-ZXkbfeXa4y+beLF_3YN-vS3CtyAKGwkg@mail.gmail.com/ Thanks, Yicong > To be more precise, > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinconfig-pin-configuration-descriptor-macro > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinfunction-pin-function-descriptor-macro > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroup-pin-group-descriptor-macro > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroupconfig-pin-group-configuration-descriptor-macro >
On Tue, Feb 08, 2022 at 10:15:44AM +0800, Yicong Yang wrote: > On 2022/2/7 19:20, Andy Shevchenko wrote: > > On Mon, Feb 07, 2022 at 01:17:49PM +0200, Andy Shevchenko wrote: > >> On Tue, Jan 25, 2022 at 08:49:29PM +0800, Yicong Yang wrote: > >>> Add generic GPIO bus recovery support for i2c-hisi driver > >>> by registering the recovery information with core provided > >>> i2c_generic_scl_recovery() method. > >>> > >>> As the SCL/SDA pins are multiplexed with GPIO, we need to > >>> switch the pins mux to GPIO before recovery and switch back > >>> after recovery. It's implemented by the ACPI method in > >>> the i2c_bus_recovery_info->{prepare,unprepare}_recovery() > >>> method. > >> > >> NAK. > >> > >> ACPI has its own resources for that. What is missed is the layer between ACPI > >> and pin control. > > I think that's where the problem is and why we use this approach. When I looked into > devm_pinctrl_get(), it stops when fails to retrieve the pin info from device tree. > So I cannot use it on our ACPI server for the pinmux. > > I looked into the history that Irina raised an RFC for adding the ACPI support in pinctrl[1], > but at that time seems it lacks some standard support. But maybe now we can support it? Not that way. ACPI has its own resources as I pointed out. Irina tried to mimic DT, which has been refused by maintainers. Since that ACPI gained the native resources. > But based on the current situation maybe the implementation of this patch suits best. > And currently we don't have a pinctrl driver for doing the multiplexing (though I think it's > easy to add one but maybe only configures 2 pins for now). This patch (i2c hisi) is a hack on all levels, starting with ACPI DSDT. Please, fix tables to use PinConfig() / PinFunction() (or corresponding *Group() variants) in the DSDT for the starter. > [1] https://lore.kernel.org/all/CACRpkdbj==q5wp2Z5-ZXkbfeXa4y+beLF_3YN-vS3CtyAKGwkg@mail.gmail.com/ > > Thanks, > Yicong > > > To be more precise, > > > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinconfig-pin-configuration-descriptor-macro > > > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pinfunction-pin-function-descriptor-macro > > > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroup-pin-group-descriptor-macro > > > > https://uefi.org/specs/ACPI/6.4/19_ASL_Reference/ACPI_Source_Language_Reference.html?highlight=pinfunction#pingroupconfig-pin-group-configuration-descriptor-macro
diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c index acf394812061..ffc495f426e9 100644 --- a/drivers/i2c/busses/i2c-hisi.c +++ b/drivers/i2c/busses/i2c-hisi.c @@ -5,9 +5,11 @@ * Copyright (c) 2021 HiSilicon Technologies Co., Ltd. */ +#include <linux/acpi.h> #include <linux/bits.h> #include <linux/bitfield.h> #include <linux/completion.h> +#include <linux/gpio/consumer.h> #include <linux/i2c.h> #include <linux/interrupt.h> #include <linux/io.h> @@ -106,6 +108,9 @@ struct hisi_i2c_controller { struct i2c_timings t; u32 clk_rate_khz; u32 spk_len; + + /* Bus recovery method */ + struct i2c_bus_recovery_info rinfo; }; static void hisi_i2c_enable_int(struct hisi_i2c_controller *ctlr, u32 mask) @@ -424,6 +429,77 @@ static void hisi_i2c_configure_bus(struct hisi_i2c_controller *ctlr) writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL); } +#ifdef CONFIG_ACPI +#define HISI_I2C_PIN_MUX_METHOD "PMUX" + +/** + * i2c_dw_acpi_pin_mux_change - Change the I2C controller's pin mux through ACPI + * @dev: device owns the SCL/SDA pin + * @to_gpio: true to switch to GPIO, false to switch to SCL/SDA + * + * The function invokes the specific ACPI method "PMUX" for changing the + * pin mux of I2C controller between SCL/SDA and GPIO in order to help on + * the generic GPIO recovery process. + */ +static void i2c_hisi_pin_mux_change(struct device *dev, bool to_gpio) +{ + acpi_handle handle = ACPI_HANDLE(dev); + struct acpi_object_list arg_list; + unsigned long long data; + union acpi_object arg; + + arg.type = ACPI_TYPE_INTEGER; + arg.integer.value = to_gpio; + arg_list.count = 1; + arg_list.pointer = &arg; + + acpi_evaluate_integer(handle, HISI_I2C_PIN_MUX_METHOD, &arg_list, &data); +} + +static void i2c_hisi_prepare_recovery(struct i2c_adapter *adap) +{ + struct hisi_i2c_controller *ctlr = i2c_get_adapdata(adap); + + i2c_hisi_pin_mux_change(ctlr->dev, true); +} + +static void i2c_hisi_unprepare_recovery(struct i2c_adapter *adap) +{ + struct hisi_i2c_controller *ctlr = i2c_get_adapdata(adap); + + i2c_hisi_pin_mux_change(ctlr->dev, false); +} + +static void hisi_i2c_init_recovery_info(struct hisi_i2c_controller *ctlr) +{ + struct i2c_bus_recovery_info *rinfo = &ctlr->rinfo; + struct acpi_device *adev = ACPI_COMPANION(ctlr->dev); + struct gpio_desc *gpio; + + if (!acpi_has_method(adev->handle, HISI_I2C_PIN_MUX_METHOD)) + return; + + gpio = devm_gpiod_get_optional(ctlr->dev, "scl", GPIOD_OUT_HIGH); + if (IS_ERR_OR_NULL(gpio)) + return; + + rinfo->scl_gpiod = gpio; + + gpio = devm_gpiod_get_optional(ctlr->dev, "sda", GPIOD_IN); + if (IS_ERR(gpio)) + return; + + rinfo->sda_gpiod = gpio; + rinfo->recover_bus = i2c_generic_scl_recovery; + rinfo->prepare_recovery = i2c_hisi_prepare_recovery; + rinfo->unprepare_recovery = i2c_hisi_unprepare_recovery; + + ctlr->adapter.bus_recovery_info = rinfo; +} +#else +static inline void hisi_i2c_init_recovery_info(struct hisi_i2c_controller *ctlr) { } +#endif /* CONFIG_ACPI */ + static int hisi_i2c_probe(struct platform_device *pdev) { struct hisi_i2c_controller *ctlr; @@ -473,6 +549,8 @@ static int hisi_i2c_probe(struct platform_device *pdev) adapter->dev.parent = dev; i2c_set_adapdata(adapter, ctlr); + hisi_i2c_init_recovery_info(ctlr); + ret = devm_i2c_add_adapter(dev, adapter); if (ret) return ret;
Add generic GPIO bus recovery support for i2c-hisi driver by registering the recovery information with core provided i2c_generic_scl_recovery() method. As the SCL/SDA pins are multiplexed with GPIO, we need to switch the pins mux to GPIO before recovery and switch back after recovery. It's implemented by the ACPI method in the i2c_bus_recovery_info->{prepare,unprepare}_recovery() method. Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> --- drivers/i2c/busses/i2c-hisi.c | 78 +++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+)