Hi Simon,
On 1/15/21 3:05 PM, Simon Glass wrote:
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 <s...@chromium.org>
---
arch/sandbox/include/asm/gpio.h | 5 +-
drivers/gpio/gpio-uclass.c | 78 ++++++++++++++++++++++++++
drivers/gpio/sandbox.c | 13 +++--
include/asm-generic/gpio.h | 37 +++++++++++++
test/dm/gpio.c | 98 +++++++++++++++++++++++++++++++++
5 files changed, 226 insertions(+), 5 deletions(-)
diff --git a/arch/sandbox/include/asm/gpio.h b/arch/sandbox/include/asm/gpio.h
index edf78cb4131..097abfb299c 100644
--- a/arch/sandbox/include/asm/gpio.h
+++ b/arch/sandbox/include/asm/gpio.h
@@ -26,8 +26,11 @@
/* Our own private GPIO flags, which musn't conflict with GPIOD_... */
#define GPIOD_EXT_HIGH BIT(20) /* external source is high
(else low) */
#define GPIOD_EXT_DRIVEN BIT(21) /* external source is driven */
+#define GPIOD_EXT_PULL_UP BIT(22) /* GPIO has external pull-up */
+#define GPIOD_EXT_PULL_DOWN BIT(23) /* GPIO has external pull-down */
-#define GPIOD_SANDBOX_MASK GENMASK(21, 20)
+#define GPIOD_EXT_PULL (BIT(21) | BIT(22))
+#define GPIOD_SANDBOX_MASK GENMASK(23, 20)
/**
* Return the simulated value of a GPIO (used only in sandbox test code)
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 77b40263bbd..984c07d1dfa 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -3,6 +3,8 @@
* Copyright (c) 2013 Google, Inc
*/
+#define LOG_CATEGORY UCLASS_GPIO
+
define for LOG feature could be a separate patch ?
to support CONFIG_LOG with existing debug() macro
#include <common.h>
#include <dm.h>
#include <log.h>
@@ -20,6 +22,7 @@
#include <dm/device_compat.h>
#include <linux/bug.h>
#include <linux/ctype.h>
+#include <linux/delay.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -708,6 +711,21 @@ int dm_gpio_set_dir_flags(struct gpio_desc *desc, ulong flags)
return dm_gpio_clrset_flags(desc, 0, 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;
@@ -974,6 +992,66 @@ 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;
+
return error if overflow for the the request count ?
when size_of(int) / 3 < count.
+ 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.
+ */
+ digit = pd;
+
+ /*
+ * If the values differ then the pin is floating so we call
+ * this a 2.
+ */
+ if (pu != pd)
+ digit |= 2;
/*
* If the values differ then the pin is floating so we call
* this a 2.
* else 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 (pu != pd)
digit = 2;
else
digit = pd;
I known that it is the same result (as in this case digit = pd = 0 and
pu = 1)
but perhaps more clear that "digit |= 2;" with OR operator
+ 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 b32f7ac529b..56b339f5e3c 100644
--- a/drivers/gpio/sandbox.c
+++ b/drivers/gpio/sandbox.c
@@ -19,7 +19,6 @@
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/gpio/sandbox-gpio.h>
-
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;
}
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 4628d937259..1cf81a3fc7a 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -505,6 +505,28 @@ int gpio_get_values_as_int(const int *gpio_list);
*/
int dm_gpio_get_values_as_int(const struct gpio_desc *desc_list, int count);
+/**
+ * dm_gpio_get_values_as_int_base3() - Create a base-3 int from a list of GPIOs
+ *
+ * This uses pull-ups/pull-downs to figure out whether a GPIO line is
externally
+ * pulled down, pulled up or floating. This allows three different strap values
+ * for each pin.
Add base 3 associated value description in function description
* 0 : external pull down
* 1 : externall pull up
* 2 : floating
+ *
+ * With this it is possible to obtain more combinations from the same number of
+ * strapping pins, when compared to dm_gpio_get_values_as_int(). The external
+ * pull resistors should be made stronger that the internal SoC pull resistors,
+ * for this to work.
+ *
+ * With 2 pins, 6 combinations are possible, compare with 4
+ * With 3 pins, 27 are possible, compared with 8
+ *
+ * @desc_list: List of GPIOs to collect
+ * @count: Number of GPIOs
+ * @return resulting integer value, or -ve on error
+ */
+int dm_gpio_get_values_as_int_base3(struct gpio_desc *desc_list,
+ int count);
+
/**
* gpio_claim_vector() - claim a number of GPIOs for input
*
(...)
For information, I am testing the feature on STM32 platform.
I hope have a result before the end of the week.
Regards
Patrick
