MIPS: Alchemy: Threaded carddetect irqs for devboards

This introduces threaded carddetect irqs for the db1200/db1300 boards.
Main benefit is that the broken insertion/ejection interrupt pairs
can now be better supported and debounced in software.

Signed-off-by: Manuel Lauss <[e-mail]>
Cc: James Hogan <[e-mail]>
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/15287/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/alchemy/devboards/db1200.c

···
 
 /* SD carddetects:  they're supposed to be edge-triggered, but ack
  * doesn't seem to work (CPLD Rev 2).  Instead, the screaming one
- * is disabled and its counterpart enabled.  The 500ms timeout is
- * because the carddetect isn't debounced in hardware.
+ * is disabled and its counterpart enabled.  The 200ms timeout is
+ * because the carddetect usually triggers twice, after debounce.
  */
 static irqreturn_t db1200_mmc_cd(int irq, void *ptr)
 {
-	void(*mmc_cd)(struct mmc_host *, unsigned long);
+	disable_irq_nosync(irq);
+	return IRQ_WAKE_THREAD;
+}
 
-	if (irq == DB1200_SD0_INSERT_INT) {
-		disable_irq_nosync(DB1200_SD0_INSERT_INT);
-		enable_irq(DB1200_SD0_EJECT_INT);
-	} else {
-		disable_irq_nosync(DB1200_SD0_EJECT_INT);
-		enable_irq(DB1200_SD0_INSERT_INT);
-	}
+static irqreturn_t db1200_mmc_cdfn(int irq, void *ptr)
+{
+	void (*mmc_cd)(struct mmc_host *, unsigned long);
 
 	/* link against CONFIG_MMC=m */
 	mmc_cd = symbol_get(mmc_detect_change);
 	if (mmc_cd) {
-		mmc_cd(ptr, msecs_to_jiffies(500));
+		mmc_cd(ptr, msecs_to_jiffies(200));
 		symbol_put(mmc_detect_change);
 	}
+
+	msleep(100);	/* debounce */
+	if (irq == DB1200_SD0_INSERT_INT)
+		enable_irq(DB1200_SD0_EJECT_INT);
+	else
+		enable_irq(DB1200_SD0_INSERT_INT);
 
 	return IRQ_HANDLED;
 }
···
 	int ret;
 
 	if (en) {
-		ret = request_irq(DB1200_SD0_INSERT_INT, db1200_mmc_cd,
-				  0, "sd_insert", mmc_host);
+		ret = request_threaded_irq(DB1200_SD0_INSERT_INT, db1200_mmc_cd,
+				db1200_mmc_cdfn, 0, "sd_insert", mmc_host);
 		if (ret)
 			goto out;
 
-		ret = request_irq(DB1200_SD0_EJECT_INT, db1200_mmc_cd,
-				  0, "sd_eject", mmc_host);
+		ret = request_threaded_irq(DB1200_SD0_EJECT_INT, db1200_mmc_cd,
+				db1200_mmc_cdfn, 0, "sd_eject", mmc_host);
 		if (ret) {
 			free_irq(DB1200_SD0_INSERT_INT, mmc_host);
 			goto out;
···
 
 static irqreturn_t pb1200_mmc1_cd(int irq, void *ptr)
 {
-	void(*mmc_cd)(struct mmc_host *, unsigned long);
+	disable_irq_nosync(irq);
+	return IRQ_WAKE_THREAD;
+}
 
-	if (irq == PB1200_SD1_INSERT_INT) {
-		disable_irq_nosync(PB1200_SD1_INSERT_INT);
-		enable_irq(PB1200_SD1_EJECT_INT);
-	} else {
-		disable_irq_nosync(PB1200_SD1_EJECT_INT);
-		enable_irq(PB1200_SD1_INSERT_INT);
-	}
+static irqreturn_t pb1200_mmc1_cdfn(int irq, void *ptr)
+{
+	void (*mmc_cd)(struct mmc_host *, unsigned long);
 
 	/* link against CONFIG_MMC=m */
 	mmc_cd = symbol_get(mmc_detect_change);
 	if (mmc_cd) {
-		mmc_cd(ptr, msecs_to_jiffies(500));
+		mmc_cd(ptr, msecs_to_jiffies(200));
 		symbol_put(mmc_detect_change);
 	}
+
+	msleep(100);	/* debounce */
+	if (irq == PB1200_SD1_INSERT_INT)
+		enable_irq(PB1200_SD1_EJECT_INT);
+	else
+		enable_irq(PB1200_SD1_INSERT_INT);
 
 	return IRQ_HANDLED;
 }
···
 	int ret;
 
 	if (en) {
-		ret = request_irq(PB1200_SD1_INSERT_INT, pb1200_mmc1_cd, 0,
-				  "sd1_insert", mmc_host);
+		ret = request_threaded_irq(PB1200_SD1_INSERT_INT, pb1200_mmc1_cd,
+				pb1200_mmc1_cdfn, 0, "sd1_insert", mmc_host);
 		if (ret)
 			goto out;
 
-		ret = request_irq(PB1200_SD1_EJECT_INT, pb1200_mmc1_cd, 0,
-				  "sd1_eject", mmc_host);
+		ret = request_threaded_irq(PB1200_SD1_EJECT_INT, pb1200_mmc1_cd,
+				pb1200_mmc1_cdfn, 0, "sd1_eject", mmc_host);
 		if (ret) {
 			free_irq(PB1200_SD1_INSERT_INT, mmc_host);
 			goto out;

arch/mips/alchemy/devboards/db1300.c

···
 
 static irqreturn_t db1300_mmc_cd(int irq, void *ptr)
 {
-	void(*mmc_cd)(struct mmc_host *, unsigned long);
+	disable_irq_nosync(irq);
+	return IRQ_WAKE_THREAD;
+}
 
-	/* disable the one currently screaming. No other way to shut it up */
-	if (irq == DB1300_SD1_INSERT_INT) {
-		disable_irq_nosync(DB1300_SD1_INSERT_INT);
-		enable_irq(DB1300_SD1_EJECT_INT);
-	} else {
-		disable_irq_nosync(DB1300_SD1_EJECT_INT);
-		enable_irq(DB1300_SD1_INSERT_INT);
-	}
+static irqreturn_t db1300_mmc_cdfn(int irq, void *ptr)
+{
+	void (*mmc_cd)(struct mmc_host *, unsigned long);
 
 	/* link against CONFIG_MMC=m.  We can only be called once MMC core has
 	 * initialized the controller, so symbol_get() should always succeed.
 	 */
 	mmc_cd = symbol_get(mmc_detect_change);
-	mmc_cd(ptr, msecs_to_jiffies(500));
+	mmc_cd(ptr, msecs_to_jiffies(200));
 	symbol_put(mmc_detect_change);
+
+	msleep(100);	/* debounce */
+	if (irq == DB1300_SD1_INSERT_INT)
+		enable_irq(DB1300_SD1_EJECT_INT);
+	else
+		enable_irq(DB1300_SD1_INSERT_INT);
 
 	return IRQ_HANDLED;
 }
···
 	int ret;
 
 	if (en) {
-		ret = request_irq(DB1300_SD1_INSERT_INT, db1300_mmc_cd, 0,
-				  "sd_insert", mmc_host);
+		ret = request_threaded_irq(DB1300_SD1_INSERT_INT, db1300_mmc_cd,
+				db1300_mmc_cdfn, 0, "sd_insert", mmc_host);
 		if (ret)
 			goto out;
 
-		ret = request_irq(DB1300_SD1_EJECT_INT, db1300_mmc_cd, 0,
-				  "sd_eject", mmc_host);
+		ret = request_threaded_irq(DB1300_SD1_EJECT_INT, db1300_mmc_cd,
+				db1300_mmc_cdfn, 0, "sd_eject", mmc_host);
 		if (ret) {
 			free_irq(DB1300_SD1_INSERT_INT, mmc_host);
 			goto out;

drivers/pcmcia/db1xxx_ss.c

···
 	return IRQ_HANDLED;
 }
 
+/* Db/Pb1200 have separate per-socket insertion and ejection
+ * interrupts which stay asserted as long as the card is
+ * inserted/missing.  The one which caused us to be called
+ * needs to be disabled and the other one enabled.
+ */
 static irqreturn_t db1200_pcmcia_cdirq(int irq, void *data)
+{
+	disable_irq_nosync(irq);
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t db1200_pcmcia_cdirq_fn(int irq, void *data)
 {
 	struct db1x_pcmcia_sock *sock = data;
 
-	/* Db/Pb1200 have separate per-socket insertion and ejection
-	 * interrupts which stay asserted as long as the card is
-	 * inserted/missing.  The one which caused us to be called
-	 * needs to be disabled and the other one enabled.
-	 */
-	if (irq == sock->insert_irq) {
-		disable_irq_nosync(sock->insert_irq);
+	/* Wait a bit for the signals to stop bouncing. */
+	msleep(100);
+	if (irq == sock->insert_irq)
 		enable_irq(sock->eject_irq);
-	} else {
-		disable_irq_nosync(sock->eject_irq);
+	else
 		enable_irq(sock->insert_irq);
-	}
 
 	pcmcia_parse_events(&sock->socket, SS_DETECT);
 
···
 	 */
 	if ((sock->board_type == BOARD_TYPE_DB1200) ||
 	    (sock->board_type == BOARD_TYPE_DB1300)) {
-		ret = request_irq(sock->insert_irq, db1200_pcmcia_cdirq,
-				  0, "pcmcia_insert", sock);
+		ret = request_threaded_irq(sock->insert_irq, db1200_pcmcia_cdirq,
+			db1200_pcmcia_cdirq_fn, 0, "pcmcia_insert", sock);
 		if (ret)
 			goto out1;
 
-		ret = request_irq(sock->eject_irq, db1200_pcmcia_cdirq,
-				  0, "pcmcia_eject", sock);
+		ret = request_threaded_irq(sock->eject_irq, db1200_pcmcia_cdirq,
+			db1200_pcmcia_cdirq_fn, 0, "pcmcia_eject", sock);
 		if (ret) {
 			free_irq(sock->insert_irq, sock);
 			goto out1;