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Message-ID: <20240905041732.2034348-13-dmitry.torokhov@gmail.com>
Date: Wed, 4 Sep 2024 21:17:17 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Pali Rohár <pali@...nel.org>,
Helge Deller <deller@....de>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>,
Dexuan Cui <decui@...rosoft.com>,
Samuel Holland <samuel@...lland.org>,
Lyude Paul <thatslyude@...il.com>,
Michal Simek <michal.simek@....com>,
Hans de Goede <hdegoede@...hat.com>,
linux-kernel@...r.kernel.org,
linux-hyperv@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-sunxi@...ts.linux.dev
Subject: [PATCH 12/24] Input: i8042 - tease apart interrupt handler
In preparation to using guard notation when acquiring mutexes and
spinlocks factor out handling of active multiplexing mode from
i8042_interrupt().
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
drivers/input/serio/i8042.c | 139 +++++++++++++++++++++---------------
1 file changed, 83 insertions(+), 56 deletions(-)
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 8ec4872b4471..674cd155ec8f 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -178,7 +178,7 @@ static unsigned char i8042_suppress_kbd_ack;
static struct platform_device *i8042_platform_device;
static struct notifier_block i8042_kbd_bind_notifier_block;
-static irqreturn_t i8042_interrupt(int irq, void *dev_id);
+static bool i8042_handle_data(int irq);
static bool (*i8042_platform_filter)(unsigned char data, unsigned char str,
struct serio *serio);
@@ -434,7 +434,7 @@ static void i8042_port_close(struct serio *serio)
* See if there is any data appeared while we were messing with
* port state.
*/
- i8042_interrupt(0, NULL);
+ i8042_handle_data(0);
}
/*
@@ -518,12 +518,68 @@ static bool i8042_filter(unsigned char data, unsigned char str,
}
/*
- * i8042_interrupt() is the most important function in this driver -
- * it handles the interrupts from the i8042, and sends incoming bytes
- * to the upper layers.
+ * i8042_handle_mux() handles case when data is coming from one of
+ * the multiplexed ports. It would be simple if not for quirks with
+ * handling errors:
+ *
+ * When MUXERR condition is signalled the data register can only contain
+ * 0xfd, 0xfe or 0xff if implementation follows the spec. Unfortunately
+ * it is not always the case. Some KBCs also report 0xfc when there is
+ * nothing connected to the port while others sometimes get confused which
+ * port the data came from and signal error leaving the data intact. They
+ * _do not_ revert to legacy mode (actually I've never seen KBC reverting
+ * to legacy mode yet, when we see one we'll add proper handling).
+ * Anyway, we process 0xfc, 0xfd, 0xfe and 0xff as timeouts, and for the
+ * rest assume that the data came from the same serio last byte
+ * was transmitted (if transmission happened not too long ago).
*/
+static int i8042_handle_mux(u8 str, u8 *data, unsigned int *dfl)
+{
+ static unsigned long last_transmit;
+ static unsigned long last_port;
+ unsigned int mux_port;
+
+ mux_port = (str >> 6) & 3;
+ *dfl = 0;
+
+ if (str & I8042_STR_MUXERR) {
+ dbg("MUX error, status is %02x, data is %02x\n",
+ str, *data);
+
+ switch (*data) {
+ default:
+ if (time_before(jiffies, last_transmit + HZ/10)) {
+ mux_port = last_port;
+ break;
+ }
+ fallthrough; /* report timeout */
+ case 0xfc:
+ case 0xfd:
+ case 0xfe:
+ *dfl = SERIO_TIMEOUT;
+ *data = 0xfe;
+ break;
+ case 0xff:
+ *dfl = SERIO_PARITY;
+ *data = 0xfe;
+ break;
+ }
+ }
-static irqreturn_t i8042_interrupt(int irq, void *dev_id)
+ last_port = mux_port;
+ last_transmit = jiffies;
+
+ return I8042_MUX_PORT_NO + mux_port;
+}
+
+/*
+ * i8042_handle_data() is the most important function in this driver -
+ * it reads the data from the i8042, determines its destination serio
+ * port, and sends received byte to the upper layers.
+ *
+ * Returns true if there was data waiting, false otherwise.
+ */
+static bool i8042_handle_data(int irq)
{
struct i8042_port *port;
struct serio *serio;
@@ -532,63 +588,24 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id)
unsigned int dfl;
unsigned int port_no;
bool filtered;
- int ret = 1;
spin_lock_irqsave(&i8042_lock, flags);
str = i8042_read_status();
if (unlikely(~str & I8042_STR_OBF)) {
spin_unlock_irqrestore(&i8042_lock, flags);
- if (irq)
- dbg("Interrupt %d, without any data\n", irq);
- ret = 0;
- goto out;
+ return false;
}
data = i8042_read_data();
if (i8042_mux_present && (str & I8042_STR_AUXDATA)) {
- static unsigned long last_transmit;
- static unsigned char last_str;
-
- dfl = 0;
- if (str & I8042_STR_MUXERR) {
- dbg("MUX error, status is %02x, data is %02x\n",
- str, data);
-/*
- * When MUXERR condition is signalled the data register can only contain
- * 0xfd, 0xfe or 0xff if implementation follows the spec. Unfortunately
- * it is not always the case. Some KBCs also report 0xfc when there is
- * nothing connected to the port while others sometimes get confused which
- * port the data came from and signal error leaving the data intact. They
- * _do not_ revert to legacy mode (actually I've never seen KBC reverting
- * to legacy mode yet, when we see one we'll add proper handling).
- * Anyway, we process 0xfc, 0xfd, 0xfe and 0xff as timeouts, and for the
- * rest assume that the data came from the same serio last byte
- * was transmitted (if transmission happened not too long ago).
- */
-
- switch (data) {
- default:
- if (time_before(jiffies, last_transmit + HZ/10)) {
- str = last_str;
- break;
- }
- fallthrough; /* report timeout */
- case 0xfc:
- case 0xfd:
- case 0xfe: dfl = SERIO_TIMEOUT; data = 0xfe; break;
- case 0xff: dfl = SERIO_PARITY; data = 0xfe; break;
- }
- }
-
- port_no = I8042_MUX_PORT_NO + ((str >> 6) & 3);
- last_str = str;
- last_transmit = jiffies;
+ port_no = i8042_handle_mux(str, &data, &dfl);
} else {
- dfl = ((str & I8042_STR_PARITY) ? SERIO_PARITY : 0) |
- ((str & I8042_STR_TIMEOUT && !i8042_notimeout) ? SERIO_TIMEOUT : 0);
+ dfl = (str & I8042_STR_PARITY) ? SERIO_PARITY : 0;
+ if ((str & I8042_STR_TIMEOUT) && !i8042_notimeout)
+ dfl |= SERIO_TIMEOUT;
port_no = (str & I8042_STR_AUXDATA) ?
I8042_AUX_PORT_NO : I8042_KBD_PORT_NO;
@@ -609,8 +626,17 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id)
if (likely(serio && !filtered))
serio_interrupt(serio, data, dfl);
- out:
- return IRQ_RETVAL(ret);
+ return true;
+}
+
+static irqreturn_t i8042_interrupt(int irq, void *dev_id)
+{
+ if (unlikely(!i8042_handle_data(irq))) {
+ dbg("Interrupt %d, without any data\n", irq);
+ return IRQ_NONE;
+ }
+
+ return IRQ_HANDLED;
}
/*
@@ -1216,13 +1242,14 @@ static int i8042_controller_resume(bool s2r_wants_reset)
if (i8042_mux_present) {
if (i8042_set_mux_mode(true, NULL) || i8042_enable_mux_ports())
pr_warn("failed to resume active multiplexor, mouse won't work\n");
- } else if (i8042_ports[I8042_AUX_PORT_NO].serio)
+ } else if (i8042_ports[I8042_AUX_PORT_NO].serio) {
i8042_enable_aux_port();
+ }
if (i8042_ports[I8042_KBD_PORT_NO].serio)
i8042_enable_kbd_port();
- i8042_interrupt(0, NULL);
+ i8042_handle_data(0);
return 0;
}
@@ -1253,7 +1280,7 @@ static int i8042_pm_suspend(struct device *dev)
static int i8042_pm_resume_noirq(struct device *dev)
{
if (i8042_forcenorestore || !pm_resume_via_firmware())
- i8042_interrupt(0, NULL);
+ i8042_handle_data(0);
return 0;
}
@@ -1290,7 +1317,7 @@ static int i8042_pm_resume(struct device *dev)
static int i8042_pm_thaw(struct device *dev)
{
- i8042_interrupt(0, NULL);
+ i8042_handle_data(0);
return 0;
}
--
2.46.0.469.g59c65b2a67-goog
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