| Message ID | 20210116180424.57331-2-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/4] mmc: mmci: Add bindings to operate CMD, CK, CKIN pins as GPIO | expand |
On Sat, Jan 16, 2021 at 7:04 PM Marek Vasut <marex@denx.de> wrote: > Add support for testing whether bus voltage level translator is present > and operational. This is useful on systems where the bus voltage level > translator is optional, as the translator can be auto-detected by the > driver and the feedback clock functionality can be disabled if it is > not present. > > This requires additional pinmux state, "init", where the CMD, CK, CKIN > lines are not configured, so they can be claimed as GPIOs early on in > probe(). The translator test sets CMD high to avoid interfering with a > card, and then verifies whether signal set on CK is detected on CKIN. > If the signal is detected, translator is present, otherwise the CKIN > feedback clock are disabled. > > Signed-off-by: Marek Vasut <marex@denx.de> > Cc: Alexandre Torgue <alexandre.torgue@st.com> > Cc: Linus Walleij <linus.walleij@linaro.org> > Cc: Ludovic Barre <ludovic.barre@st.com> > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: linux-stm32@st-md-mailman.stormreply.com Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
On 1/16/21 7:04 PM, Marek Vasut wrote: > Add support for testing whether bus voltage level translator is present > and operational. This is useful on systems where the bus voltage level > translator is optional, as the translator can be auto-detected by the > driver and the feedback clock functionality can be disabled if it is > not present. > > This requires additional pinmux state, "init", where the CMD, CK, CKIN > lines are not configured, so they can be claimed as GPIOs early on in > probe(). The translator test sets CMD high to avoid interfering with a > card, and then verifies whether signal set on CK is detected on CKIN. > If the signal is detected, translator is present, otherwise the CKIN > feedback clock are disabled. > > Signed-off-by: Marek Vasut<marex@denx.de> > Cc: Alexandre Torgue<alexandre.torgue@st.com> > Cc: Linus Walleij<linus.walleij@linaro.org> > Cc: Ludovic Barre<ludovic.barre@st.com> > Cc: Ulf Hansson<ulf.hansson@linaro.org> > Cc:linux-stm32@st-md-mailman.stormreply.com Hi Marek, I've tested it on STM32MP157C-EV1 (which uses st,use-ckin) and STM32MP157C-DK2 (which doesn't). The mmc_test sessions are OK on both boards. Feel free to add my: Tested-by: Yann Gautier <yann.gautier@foss.st.com> Regards, Yann
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index b5a41a7ce165..1bc674577ff9 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -36,6 +36,7 @@ #include <linux/types.h> #include <linux/pinctrl/consumer.h> #include <linux/reset.h> +#include <linux/gpio/consumer.h> #include <asm/div64.h> #include <asm/io.h> @@ -1888,6 +1889,65 @@ static struct mmc_host_ops mmci_ops = { .start_signal_voltage_switch = mmci_sig_volt_switch, }; +static void mmci_probe_level_translator(struct mmc_host *mmc) +{ + struct device *dev = mmc_dev(mmc); + struct mmci_host *host = mmc_priv(mmc); + struct gpio_desc *cmd_gpio; + struct gpio_desc *ck_gpio; + struct gpio_desc *ckin_gpio; + int clk_hi, clk_lo; + + /* + * Assume the level translator is present if st,use-ckin is set. + * This is to cater for DTs which do not implement this test. + */ + host->clk_reg_add |= MCI_STM32_CLK_SELCKIN; + + cmd_gpio = gpiod_get(dev, "st,cmd", GPIOD_OUT_HIGH); + if (IS_ERR(cmd_gpio)) + goto exit_cmd; + + ck_gpio = gpiod_get(dev, "st,ck", GPIOD_OUT_HIGH); + if (IS_ERR(ck_gpio)) + goto exit_ck; + + ckin_gpio = gpiod_get(dev, "st,ckin", GPIOD_IN); + if (IS_ERR(ckin_gpio)) + goto exit_ckin; + + /* All GPIOs are valid, test whether level translator works */ + + /* Sample CKIN */ + clk_hi = !!gpiod_get_value(ckin_gpio); + + /* Set CK low */ + gpiod_set_value(ck_gpio, 0); + + /* Sample CKIN */ + clk_lo = !!gpiod_get_value(ckin_gpio); + + /* Tristate all */ + gpiod_direction_input(cmd_gpio); + gpiod_direction_input(ck_gpio); + + /* Level translator is present if CK signal is propagated to CKIN */ + if (!clk_hi || clk_lo) { + host->clk_reg_add &= ~MCI_STM32_CLK_SELCKIN; + dev_warn(dev, + "Level translator inoperable, CK signal not detected on CKIN, disabling.\n"); + } + + gpiod_put(ckin_gpio); + +exit_ckin: + gpiod_put(ck_gpio); +exit_ck: + gpiod_put(cmd_gpio); +exit_cmd: + pinctrl_select_default_state(dev); +} + static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc) { struct mmci_host *host = mmc_priv(mmc); @@ -1913,7 +1973,7 @@ static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc) if (of_get_property(np, "st,neg-edge", NULL)) host->clk_reg_add |= MCI_STM32_CLK_NEGEDGE; if (of_get_property(np, "st,use-ckin", NULL)) - host->clk_reg_add |= MCI_STM32_CLK_SELCKIN; + mmci_probe_level_translator(mmc); if (of_get_property(np, "mmc-cap-mmc-highspeed", NULL)) mmc->caps |= MMC_CAP_MMC_HIGHSPEED; @@ -1949,15 +2009,15 @@ static int mmci_probe(struct amba_device *dev, if (!mmc) return -ENOMEM; - ret = mmci_of_parse(np, mmc); - if (ret) - goto host_free; - host = mmc_priv(mmc); host->mmc = mmc; host->mmc_ops = &mmci_ops; mmc->ops = &mmci_ops; + ret = mmci_of_parse(np, mmc); + if (ret) + goto host_free; + /* * Some variant (STM32) doesn't have opendrain bit, nevertheless * pins can be set accordingly using pinctrl
Add support for testing whether bus voltage level translator is present and operational. This is useful on systems where the bus voltage level translator is optional, as the translator can be auto-detected by the driver and the feedback clock functionality can be disabled if it is not present. This requires additional pinmux state, "init", where the CMD, CK, CKIN lines are not configured, so they can be claimed as GPIOs early on in probe(). The translator test sets CMD high to avoid interfering with a card, and then verifies whether signal set on CK is detected on CKIN. If the signal is detected, translator is present, otherwise the CKIN feedback clock are disabled. Signed-off-by: Marek Vasut <marex@denx.de> Cc: Alexandre Torgue <alexandre.torgue@st.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Ludovic Barre <ludovic.barre@st.com> Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: linux-stm32@st-md-mailman.stormreply.com --- drivers/mmc/host/mmci.c | 70 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 5 deletions(-)