x1000: revamp MSC driver card detection logic

Debounce logic now handles both removal and insertion and verifies
the detection is stable for 100ms before taking any action.

This solves the bootloader "file not found" issue on the Shanling Q1.
It seems a false removal event was generated, causing the filesystem
to be automatically unmounted. Probably this is due to some transient
noise at boot. Delays didn't solve the problem, probably because the
bogus hotplug event was queued, and normal mdelay() would simply delay
event delivery.

Change-Id: I8b03fb3550309f5a7ab4be0be7465a3dab2d3450

2 files changed, 29 insertions, 17 deletions

diff --git a/firmware/target/mips/ingenic_x1000/msc-x1000.c b/firmware/target/mips/ingenic_x1000/msc-x1000.c
index 27929cced5..3b7df1dd01 100644
--- a/firmware/target/mips/ingenic_x1000/msc-x1000.c
+++ b/firmware/target/mips/ingenic_x1000/msc-x1000.c
@@ -39,6 +39,8 @@
  * ensure that removing the card always resets the driver to a sane state.
  */
 
+#define DEBOUNCE_TIME (HZ/10)
+
 static const msc_config msc_configs[] = {
 #ifdef FIIO_M3K
 #define MSC_CLOCK_SOURCE X1000_CLK_SCLK_A
@@ -105,6 +107,7 @@ static void msc_init_one(msc_drv* d, int msc)
     d->req = NULL;
     d->iflag_done = 0;
     d->card_present = 1;
+    d->card_present_last = 1;
     d->req_running = 0;
     mutex_init(&d->lock);
     semaphore_init(&d->cmd_done, 1, 0);
@@ -122,8 +125,10 @@ static void msc_init_one(msc_drv* d, int msc)
 
     /* Setup the card detect IRQ */
     if(d->config->cd_gpio != GPIO_NONE) {
-        if(gpio_get_level(d->config->cd_gpio) != d->config->cd_active_level)
+        if(gpio_get_level(d->config->cd_gpio) != d->config->cd_active_level) {
             d->card_present = 0;
+            d->card_present_last = 0;
+        }
 
         system_set_irq_handler(GPIO_TO_IRQ(d->config->cd_gpio),
                                msc == 0 ? msc0_cd_interrupt : msc1_cd_interrupt);
@@ -613,11 +618,25 @@ static void msc_interrupt(msc_drv* d)
 static int msc_cd_callback(struct timeout* tmo)
 {
     msc_drv* d = (msc_drv*)tmo->data;
+    int now_present = msc_card_detect(d) ? 1 : 0;
+
+    /* If the CD pin level changed during the timeout interval, then the
+     * signal is not yet stable and we need to wait longer. */
+    if(now_present != d->card_present_last) {
+        d->card_present_last = now_present;
+        return DEBOUNCE_TIME;
+    }
 
-    /* If card is still present we assume the card is properly inserted */
-    if(msc_card_detect(d)) {
-        d->card_present = 1;
-        queue_broadcast(SYS_HOTSWAP_INSERTED, d->drive_nr);
+    /* If there is a change, then broadcast the hotswap event */
+    if(now_present != d->card_present) {
+        if(now_present) {
+            d->card_present = 1;
+            queue_broadcast(SYS_HOTSWAP_INSERTED, d->drive_nr);
+        } else {
+            msc_async_abort(d, MSC_REQ_EXTRACTED);
+            d->card_present = 0;
+            queue_broadcast(SYS_HOTSWAP_EXTRACTED, d->drive_nr);
+        }
     }
 
     return 0;
@@ -625,17 +644,9 @@ static int msc_cd_callback(struct timeout* tmo)
 
 static void msc_cd_interrupt(msc_drv* d)
 {
-    if(!msc_card_detect(d)) {
-        /* Immediately abort and notify when removing a card */
-        msc_async_abort(d, MSC_REQ_EXTRACTED);
-        if(d->card_present) {
-            d->card_present = 0;
-            queue_broadcast(SYS_HOTSWAP_EXTRACTED, d->drive_nr);
-        }
-    } else {
-        /* Timer to debounce input */
-        timeout_register(&d->cd_tmo, msc_cd_callback, HZ/4, (intptr_t)d);
-    }
+    /* Timer to debounce input */
+    d->card_present_last = msc_card_detect(d) ? 1 : 0;
+    timeout_register(&d->cd_tmo, msc_cd_callback, DEBOUNCE_TIME, (intptr_t)d);
 
     /* Invert the IRQ */
     gpio_flip_edge_irq(d->config->cd_gpio);
diff --git a/firmware/target/mips/ingenic_x1000/msc-x1000.h b/firmware/target/mips/ingenic_x1000/msc-x1000.h
index 70f67a70d6..b7b05b859d 100644
--- a/firmware/target/mips/ingenic_x1000/msc-x1000.h
+++ b/firmware/target/mips/ingenic_x1000/msc-x1000.h
@@ -126,7 +126,8 @@ typedef struct msc_drv {
     unsigned iflag_done;
 
     volatile int req_running;
-    volatile int card_present;
+    volatile int card_present; /* Debounced status */
+    volatile int card_present_last; /* Status when we last polled it */
 
     struct mutex lock;
     struct semaphore cmd_done;