From 8a45b2205749252f61d26508d5de9dcce020b2ef Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Thu, 4 Feb 2021 21:22:09 -0700 Subject: gpio: Add a way to read 3-way strapping pins Using the internal vs. external pull resistors it is possible to get 27 different combinations from 3 strapping pins. Add an implementation of this. This involves updating the sandbox GPIO driver to model external and (weaker) internal pull resistors. The get_value() method now takes account of what is driving a pin: sandbox: GPIOD_EXT_DRIVEN - in which case GPIO_EXT_HIGH provides the value outside source - in which case GPIO_EXT_PULL_UP/DOWN indicates the external state and we work the final state using those flags and the internal GPIOD_PULL_UP/DOWN flags Of course the outside source does not really exist in sandbox. We are just modelling it for test purpose. Signed-off-by: Simon Glass --- drivers/gpio/gpio-uclass.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++ drivers/gpio/sandbox.c | 13 +++++--- 2 files changed, 90 insertions(+), 4 deletions(-) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c index 729e41033b..f24db87ef0 100644 --- a/drivers/gpio/gpio-uclass.c +++ b/drivers/gpio/gpio-uclass.c @@ -23,6 +23,7 @@ #include #include #include +#include DECLARE_GLOBAL_DATA_PTR; @@ -723,6 +724,21 @@ int dm_gpio_set_dir(struct gpio_desc *desc) return _dm_gpio_set_flags(desc, desc->flags); } +int dm_gpios_clrset_flags(struct gpio_desc *desc, int count, ulong clr, + ulong set) +{ + int ret; + int i; + + for (i = 0; i < count; i++) { + ret = dm_gpio_clrset_flags(&desc[i], clr, set); + if (ret) + return log_ret(ret); + } + + return 0; +} + int dm_gpio_get_flags(struct gpio_desc *desc, ulong *flagsp) { struct udevice *dev = desc->dev; @@ -989,6 +1005,71 @@ int dm_gpio_get_values_as_int(const struct gpio_desc *desc_list, int count) return vector; } +int dm_gpio_get_values_as_int_base3(struct gpio_desc *desc_list, + int count) +{ + static const char tristate[] = "01z"; + enum { + PULLUP, + PULLDOWN, + + NUM_OPTIONS, + }; + int vals[NUM_OPTIONS]; + uint mask; + uint vector = 0; + int ret, i; + + /* + * Limit to 19 digits which should be plenty. This avoids overflow of a + * 32-bit int + */ + assert(count < 20); + + for (i = 0; i < NUM_OPTIONS; i++) { + uint flags = GPIOD_IS_IN; + + flags |= (i == PULLDOWN) ? GPIOD_PULL_DOWN : GPIOD_PULL_UP; + ret = dm_gpios_clrset_flags(desc_list, count, GPIOD_MASK_PULL, + flags); + if (ret) + return log_msg_ret("pu", ret); + + /* Give the lines time to settle */ + udelay(10); + + ret = dm_gpio_get_values_as_int(desc_list, count); + if (ret < 0) + return log_msg_ret("get1", ret); + vals[i] = ret; + } + + log_debug("values: %x %x, count = %d\n", vals[0], vals[1], count); + for (i = count - 1, mask = 1 << i; i >= 0; i--, mask >>= 1) { + uint pd = vals[PULLDOWN] & mask ? 1 : 0; + uint pu = vals[PULLUP] & mask ? 1 : 0; + uint digit; + + /* + * Get value with internal pulldown active. If this is 1 then + * there is a stronger external pullup, which we call 1. If not + * then call it 0. + * + * If the values differ then the pin is floating so we call + * this a 2. + */ + if (pu == pd) + digit = pd; + else + digit = 2; + log_debug("%c ", tristate[digit]); + vector = 3 * vector + digit; + } + log_debug("vector=%d\n", vector); + + return vector; +} + /** * gpio_request_tail: common work for requesting a gpio. * diff --git a/drivers/gpio/sandbox.c b/drivers/gpio/sandbox.c index 700098446b..d008fdd222 100644 --- a/drivers/gpio/sandbox.c +++ b/drivers/gpio/sandbox.c @@ -19,7 +19,6 @@ #include #include - struct gpio_state { const char *label; /* label given by requester */ ulong flags; /* flags (GPIOD_...) */ @@ -81,10 +80,16 @@ int sandbox_gpio_get_value(struct udevice *dev, unsigned offset) if (get_gpio_flag(dev, offset, GPIOD_IS_OUT)) debug("sandbox_gpio: get_value on output gpio %u\n", offset); - if (state->flags & GPIOD_EXT_DRIVEN) + if (state->flags & GPIOD_EXT_DRIVEN) { val = state->flags & GPIOD_EXT_HIGH; - else - val = false; + } else { + if (state->flags & GPIOD_EXT_PULL_UP) + val = true; + else if (state->flags & GPIOD_EXT_PULL_DOWN) + val = false; + else + val = state->flags & GPIOD_PULL_UP; + } return val; } -- cgit v1.2.3