ioexpander: Introduce GPIO save and restore functions

Add common ioexpander functions for saving a restoring GPIO state. This
is useful for restoring GPIO after the ioexpander is reset.

BUG=b:211452276
BRANCH=None
TEST=ioexpander state restored on nipperkin

Change-Id: Id81c5457f1c33fdf7490a963317e11a2b9441831
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3368321
Reviewed-by: Diana Z <dzigterman@chromium.org>

2 files changed, 74 insertions, 0 deletions

diff --git a/common/ioexpander.c b/common/ioexpander.c
index 6caa7f4bc1..2bed1039f4 100644
--- a/common/ioexpander.c
+++ b/common/ioexpander.c
@@ -154,6 +154,60 @@ int ioex_get_port(int ioex, int port, int *val)
 }
 #endif
 
+int ioex_save_gpio_state(int ioex, int *state, int state_len)
+{
+	int rv;
+	const struct ioex_info *g = ioex_list;
+	const struct ioexpander_drv *drv = ioex_config[ioex].drv;
+	int state_offset = 0;
+
+	for (int i = 0; i < IOEX_COUNT; i++, g++) {
+		if (g->ioex != ioex)
+			continue;
+
+		if (state_offset >= state_len) {
+			CPRINTS("%s state buffer is too small", __func__);
+			return EC_ERROR_UNKNOWN;
+		}
+
+		rv = drv->get_flags_by_mask(g->ioex, g->port, g->mask,
+					    &state[state_offset++]);
+		if (rv) {
+			CPRINTS("%s failed to get flags rv=%d", __func__, rv);
+			return rv;
+		}
+	}
+
+	return EC_SUCCESS;
+}
+
+int ioex_restore_gpio_state(int ioex, const int *state, int state_len)
+{
+	int rv;
+	const struct ioex_info *g = ioex_list;
+	const struct ioexpander_drv *drv = ioex_config[ioex].drv;
+	int state_offset = 0;
+
+	for (int i = 0; i < IOEX_COUNT; i++, g++) {
+		if (g->ioex != ioex)
+			continue;
+
+		if (state_offset >= state_len) {
+			CPRINTS("%s state buffer is too small", __func__);
+			return EC_ERROR_UNKNOWN;
+		}
+
+		rv = drv->set_flags_by_mask(g->ioex, g->port, g->mask,
+				       state[state_offset++]);
+		if (rv) {
+			CPRINTS("%s failed to set flags rv=%d", __func__, rv);
+			return rv;
+		}
+	}
+
+	return EC_SUCCESS;
+}
+
 int ioex_init(int ioex)
 {
 	const struct ioex_info *g = ioex_list;
diff --git a/include/ioexpander.h b/include/ioexpander.h
index 4024a5a267..fb47b874a5 100644
--- a/include/ioexpander.h
+++ b/include/ioexpander.h
@@ -179,4 +179,24 @@ const char *ioex_get_name(enum ioex_signal signal);
  */
 int signal_is_ioex(int signal);
 
+/*
+ * Save gpio state of IO expander
+ *
+ * @param ioex		IO expander chip's port number
+ * @param state		Buffer to hold gpio state
+ * @param state_len	Length of state buffer, IOEX_COUNT is recommended
+ * @return		EC_SUCCESS if successful, non-zero if error.
+ */
+int ioex_save_gpio_state(int ioex, int *state, int state_len);
+
+/*
+ * Restore gpio state of IO expander
+ *
+ * @param ioex		IO expander chip's port number
+ * @param state		Buffer with gpio state saved by ioex_save_gpio_state
+ * @param state_len	Length of state buffer, IOEX_COUNT is recommended
+ * @return		EC_SUCCESS if successful, non-zero if error.
+ */
+int ioex_restore_gpio_state(int ioex, const int *state, int state_len);
+
 #endif /* __CROS_EC_IOEXPANDER_H */