Input: libps2 - introduce common interrupt handler

Instead of exposing inner workings of libps2 to drivers such as atkbd and
psmouse, have them define pre-receive and receive callbacks, and provide a
common handler that can be used with underlying serio port.

While at this add kerneldoc to the module.

Link: https://lore.kernel.org/r/ZGK81cxqjr/KS1kA@google.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/atkbd.c

@@ -399,46 +399,60 @@ static unsigned int atkbd_compat_scancode(struct atkbd *atkbd, unsigned int code
 }
 
 /*
- * atkbd_interrupt(). Here takes place processing of data received from
- * the keyboard into events.
+ * Tries to handle frame or parity error by requesting the keyboard controller
+ * to resend the last byte. This historically not done on x86 as controllers
+ * there typically do not implement this command.
  */
-
-static irqreturn_t atkbd_interrupt(struct serio *serio, unsigned char data,
-				   unsigned int flags)
+static bool __maybe_unused atkbd_handle_frame_error(struct ps2dev *ps2dev,
+						    u8 data, unsigned int flags)
 {
-	struct atkbd *atkbd = atkbd_from_serio(serio);
-	struct input_dev *dev = atkbd->dev;
-	unsigned int code = data;
-	int scroll = 0, hscroll = 0, click = -1;
-	int value;
-	unsigned short keycode;
+	struct atkbd *atkbd = container_of(ps2dev, struct atkbd, ps2dev);
+	struct serio *serio = ps2dev->serio;
 
-	dev_dbg(&serio->dev, "Received %02x flags %02x\n", data, flags);
-
-#if !defined(__i386__) && !defined (__x86_64__)
-	if ((flags & (SERIO_FRAME | SERIO_PARITY)) && (~flags & SERIO_TIMEOUT) && !atkbd->resend && atkbd->write) {
+	if ((flags & (SERIO_FRAME | SERIO_PARITY)) &&
+	    (~flags & SERIO_TIMEOUT) &&
+	    !atkbd->resend && atkbd->write) {
 		dev_warn(&serio->dev, "Frame/parity error: %02x\n", flags);
 		serio_write(serio, ATKBD_CMD_RESEND);
 		atkbd->resend = true;
-		goto out;
+		return true;
 	}
 
 	if (!flags && data == ATKBD_RET_ACK)
 		atkbd->resend = false;
+
+	return false;
+}
+
+static enum ps2_disposition atkbd_pre_receive_byte(struct ps2dev *ps2dev,
+						   u8 data, unsigned int flags)
+{
+	struct serio *serio = ps2dev->serio;
+
+	dev_dbg(&serio->dev, "Received %02x flags %02x\n", data, flags);
+
+#if !defined(__i386__) && !defined (__x86_64__)
+	if (atkbd_handle_frame_error(ps2dev, data, flags))
+		return PS2_IGNORE;
 #endif
 
-	if (unlikely(atkbd->ps2dev.flags & PS2_FLAG_ACK))
-		if  (ps2_handle_ack(&atkbd->ps2dev, data))
-			goto out;
+	return PS2_PROCESS;
+}
 
-	if (unlikely(atkbd->ps2dev.flags & PS2_FLAG_CMD))
-		if  (ps2_handle_response(&atkbd->ps2dev, data))
-			goto out;
+static void atkbd_receive_byte(struct ps2dev *ps2dev, u8 data)
+{
+	struct serio *serio = ps2dev->serio;
+	struct atkbd *atkbd = container_of(ps2dev, struct atkbd, ps2dev);
+	struct input_dev *dev = atkbd->dev;
+	unsigned int code = data;
+	int scroll = 0, hscroll = 0, click = -1;
+	int value;
+	unsigned short keycode;
 
 	pm_wakeup_event(&serio->dev, 0);
 
 	if (!atkbd->enabled)
-		goto out;
+		return;
 
 	input_event(dev, EV_MSC, MSC_RAW, code);
 
@@ -460,16 +474,16 @@ static irqreturn_t atkbd_interrupt(struct serio *serio, unsigned char data,
 	case ATKBD_RET_BAT:
 		atkbd->enabled = false;
 		serio_reconnect(atkbd->ps2dev.serio);
-		goto out;
+		return;
 	case ATKBD_RET_EMUL0:
 		atkbd->emul = 1;
-		goto out;
+		return;
 	case ATKBD_RET_EMUL1:
 		atkbd->emul = 2;
-		goto out;
+		return;
 	case ATKBD_RET_RELEASE:
 		atkbd->release = true;
-		goto out;
+		return;
 	case ATKBD_RET_ACK:
 	case ATKBD_RET_NAK:
 		if (printk_ratelimit())
@@ -477,18 +491,18 @@ static irqreturn_t atkbd_interrupt(struct serio *serio, unsigned char data,
 				 "Spurious %s on %s. "
 				 "Some program might be trying to access hardware directly.\n",
 				 data == ATKBD_RET_ACK ? "ACK" : "NAK", serio->phys);
-		goto out;
+		return;
 	case ATKBD_RET_ERR:
 		atkbd->err_count++;
 		dev_dbg(&serio->dev, "Keyboard on %s reports too many keys pressed.\n",
 			serio->phys);
-		goto out;
+		return;
 	}
 
 	code = atkbd_compat_scancode(atkbd, code);
 
 	if (atkbd->emul && --atkbd->emul)
-		goto out;
+		return;
 
 	keycode = atkbd->keycode[code];
 
@@ -564,8 +578,6 @@ static irqreturn_t atkbd_interrupt(struct serio *serio, unsigned char data,
 	}
 
 	atkbd->release = false;
-out:
-	return IRQ_HANDLED;
 }
 
 static int atkbd_set_repeat_rate(struct atkbd *atkbd)
@@ -1229,7 +1241,8 @@ static int atkbd_connect(struct serio *serio, struct serio_driver *drv)
 		goto fail1;
 
 	atkbd->dev = dev;
-	ps2_init(&atkbd->ps2dev, serio);
+	ps2_init(&atkbd->ps2dev, serio,
+		 atkbd_pre_receive_byte, atkbd_receive_byte);
 	INIT_DELAYED_WORK(&atkbd->event_work, atkbd_event_work);
 	mutex_init(&atkbd->mutex);
 
@@ -1385,7 +1398,7 @@ static struct serio_driver atkbd_drv = {
 	},
 	.description	= DRIVER_DESC,
 	.id_table	= atkbd_serio_ids,
-	.interrupt	= atkbd_interrupt,
+	.interrupt	= ps2_interrupt,
 	.connect	= atkbd_connect,
 	.reconnect	= atkbd_reconnect,
 	.disconnect	= atkbd_disconnect,

drivers/input/mouse/psmouse-base.c

@@ -336,17 +336,14 @@ static void psmouse_handle_oob_data(struct psmouse *psmouse, u8 data)
 	}
 }
 
-/*
- * psmouse_interrupt() handles incoming characters, either passing them
- * for normal processing or gathering them as command response.
- */
-static irqreturn_t psmouse_interrupt(struct serio *serio,
-				     u8 data, unsigned int flags)
+static enum ps2_disposition psmouse_pre_receive_byte(struct ps2dev *ps2dev,
+						     u8 data,
+						     unsigned int flags)
 {
-	struct psmouse *psmouse = psmouse_from_serio(serio);
+	struct psmouse *psmouse = container_of(ps2dev, struct psmouse, ps2dev);
 
 	if (psmouse->state == PSMOUSE_IGNORE)
-		goto out;
+		return PS2_IGNORE;
 
 	if (unlikely((flags & SERIO_TIMEOUT) ||
 		     ((flags & SERIO_PARITY) &&
@@ -357,27 +354,25 @@ static irqreturn_t psmouse_interrupt(struct serio *serio,
 				     "bad data from KBC -%s%s\n",
 				     flags & SERIO_TIMEOUT ? " timeout" : "",
 				     flags & SERIO_PARITY ? " bad parity" : "");
-		ps2_cmd_aborted(&psmouse->ps2dev);
-		goto out;
+		return PS2_ERROR;
 	}
 
 	if (flags & SERIO_OOB_DATA) {
 		psmouse_handle_oob_data(psmouse, data);
-		goto out;
+		return PS2_IGNORE;
 	}
 
-	if (unlikely(psmouse->ps2dev.flags & PS2_FLAG_ACK))
-		if  (ps2_handle_ack(&psmouse->ps2dev, data))
-			goto out;
+	return PS2_PROCESS;
+}
 
-	if (unlikely(psmouse->ps2dev.flags & PS2_FLAG_CMD))
-		if  (ps2_handle_response(&psmouse->ps2dev, data))
-			goto out;
+static void psmouse_receive_byte(struct ps2dev *ps2dev, u8 data)
+{
+	struct psmouse *psmouse = container_of(ps2dev, struct psmouse, ps2dev);
 
-	pm_wakeup_event(&serio->dev, 0);
+	pm_wakeup_event(&ps2dev->serio->dev, 0);
 
 	if (psmouse->state <= PSMOUSE_RESYNCING)
-		goto out;
+		return;
 
 	if (psmouse->state == PSMOUSE_ACTIVATED &&
 	    psmouse->pktcnt && time_after(jiffies, psmouse->last + HZ/2)) {
@@ -386,7 +381,7 @@ static irqreturn_t psmouse_interrupt(struct serio *serio,
 		psmouse->badbyte = psmouse->packet[0];
 		__psmouse_set_state(psmouse, PSMOUSE_RESYNCING);
 		psmouse_queue_work(psmouse, &psmouse->resync_work, 0);
-		goto out;
+		return;
 	}
 
 	psmouse->packet[psmouse->pktcnt++] = data;
@@ -395,21 +390,21 @@ static irqreturn_t psmouse_interrupt(struct serio *serio,
 	if (unlikely(psmouse->packet[0] == PSMOUSE_RET_BAT && psmouse->pktcnt <= 2)) {
 		if (psmouse->pktcnt == 1) {
 			psmouse->last = jiffies;
-			goto out;
+			return;
 		}
 
 		if (psmouse->packet[1] == PSMOUSE_RET_ID ||
 		    (psmouse->protocol->type == PSMOUSE_HGPK &&
 		     psmouse->packet[1] == PSMOUSE_RET_BAT)) {
 			__psmouse_set_state(psmouse, PSMOUSE_IGNORE);
-			serio_reconnect(serio);
-			goto out;
+			serio_reconnect(ps2dev->serio);
+			return;
 		}
 
 		/* Not a new device, try processing first byte normally */
 		psmouse->pktcnt = 1;
 		if (psmouse_handle_byte(psmouse))
-			goto out;
+			return;
 
 		psmouse->packet[psmouse->pktcnt++] = data;
 	}
@@ -424,14 +419,11 @@ static irqreturn_t psmouse_interrupt(struct serio *serio,
 		psmouse->badbyte = psmouse->packet[0];
 		__psmouse_set_state(psmouse, PSMOUSE_RESYNCING);
 		psmouse_queue_work(psmouse, &psmouse->resync_work, 0);
-		goto out;
+		return;
 	}
 
 	psmouse->last = jiffies;
 	psmouse_handle_byte(psmouse);
-
- out:
-	return IRQ_HANDLED;
 }
 
 /*
@@ -1604,7 +1596,8 @@ static int psmouse_connect(struct serio *serio, struct serio_driver *drv)
 	if (!psmouse || !input_dev)
 		goto err_free;
 
-	ps2_init(&psmouse->ps2dev, serio);
+	ps2_init(&psmouse->ps2dev, serio,
+		 psmouse_pre_receive_byte, psmouse_receive_byte);
 	INIT_DELAYED_WORK(&psmouse->resync_work, psmouse_resync);
 	psmouse->dev = input_dev;
 	snprintf(psmouse->phys, sizeof(psmouse->phys), "%s/input0", serio->phys);
@@ -1786,7 +1779,7 @@ static struct serio_driver psmouse_drv = {
 	},
 	.description	= DRIVER_DESC,
 	.id_table	= psmouse_serio_ids,
-	.interrupt	= psmouse_interrupt,
+	.interrupt	= ps2_interrupt,
 	.connect	= psmouse_connect,
 	.reconnect	= psmouse_reconnect,
 	.fast_reconnect	= psmouse_fast_reconnect,

include/linux/libps2.h

@@ -8,43 +8,59 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/interrupt.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
 #include <linux/wait.h>
 
-#define PS2_CMD_SETSCALE11	0x00e6
-#define PS2_CMD_SETRES		0x10e8
-#define PS2_CMD_GETID		0x02f2
-#define PS2_CMD_RESET_BAT	0x02ff
+struct ps2dev;
 
-#define PS2_RET_BAT		0xaa
-#define PS2_RET_ID		0x00
-#define PS2_RET_ACK		0xfa
-#define PS2_RET_NAK		0xfe
-#define PS2_RET_ERR		0xfc
+/**
+ * enum ps2_disposition - indicates how received byte should be handled
+ * @PS2_PROCESS: pass to the main protocol handler, process normally
+ * @PS2_IGNORE: skip the byte
+ * @PS2_ERROR: do not process the byte, abort command in progress
+ */
+enum ps2_disposition {
+	PS2_PROCESS,
+	PS2_IGNORE,
+	PS2_ERROR,
+};
 
-#define PS2_FLAG_ACK		BIT(0)	/* Waiting for ACK/NAK */
-#define PS2_FLAG_CMD		BIT(1)	/* Waiting for a command to finish */
-#define PS2_FLAG_CMD1		BIT(2)	/* Waiting for the first byte of command response */
-#define PS2_FLAG_WAITID		BIT(3)	/* Command executing is GET ID */
-#define PS2_FLAG_NAK		BIT(4)	/* Last transmission was NAKed */
+typedef enum ps2_disposition (*ps2_pre_receive_handler_t)(struct ps2dev *, u8,
+							  unsigned int);
+typedef void (*ps2_receive_handler_t)(struct ps2dev *, u8);
 
+/**
+ * struct ps2dev - represents a device using PS/2 protocol
+ * @serio: a serio port used by the PS/2 device
+ * @cmd_mutex: a mutex ensuring that only one command is executing at a time
+ * @wait: a waitqueue used to signal completion from the serio interrupt handler
+ * @flags: various internal flags indicating stages of PS/2 command execution
+ * @cmdbuf: buffer holding command response
+ * @cmdcnt: outstanding number of bytes of the command response
+ * @nak: a byte transmitted by the device when it refuses command
+ * @pre_receive_handler: checks communication errors and returns disposition
+ * (&enum ps2_disposition) of the received data byte
+ * @receive_handler: main handler of particular PS/2 protocol, such as keyboard
+ *   or mouse protocol
+ */
 struct ps2dev {
 	struct serio *serio;
-
-	/* Ensures that only one command is executing at a time */
 	struct mutex cmd_mutex;
-
-	/* Used to signal completion from interrupt handler */
 	wait_queue_head_t wait;
-
 	unsigned long flags;
 	u8 cmdbuf[8];
 	u8 cmdcnt;
 	u8 nak;
+
+	ps2_pre_receive_handler_t pre_receive_handler;
+	ps2_receive_handler_t receive_handler;
 };
 
-void ps2_init(struct ps2dev *ps2dev, struct serio *serio);
+void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
+	      ps2_pre_receive_handler_t pre_receive_handler,
+	      ps2_receive_handler_t receive_handler);
 int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout);
 void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout);
 void ps2_begin_command(struct ps2dev *ps2dev);
@@ -52,9 +68,8 @@ void ps2_end_command(struct ps2dev *ps2dev);
 int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command);
 int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command);
 int ps2_sliced_command(struct ps2dev *ps2dev, u8 command);
-bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data);
-bool ps2_handle_response(struct ps2dev *ps2dev, u8 data);
-void ps2_cmd_aborted(struct ps2dev *ps2dev);
 bool ps2_is_keyboard_id(u8 id);
 
+irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags);
+
 #endif /* _LIBPS2_H */