serial: sc16is7xx: change EFR lock to operate on each channels

Now that the driver has been converted to use one regmap per port, change
efr locking to operate on a channel basis instead of on the whole IC.

Fixes: 3837a03 ("serial: sc16is7xx: improve regmap debugfs by using one regmap per port")
Cc:  <stable@vger.kernel.org> # 6.1.x: 3837a03 serial: sc16is7xx: improve regmap debugfs by using one regmap per port
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231211171353.2901416-5-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sc16is7xx.c

@@ -323,6 +323,7 @@ struct sc16is7xx_one_config {
 struct sc16is7xx_one {
 	struct uart_port		port;
 	struct regmap			*regmap;
+	struct mutex			efr_lock; /* EFR registers access */
 	struct kthread_work		tx_work;
 	struct kthread_work		reg_work;
 	struct kthread_delayed_work	ms_work;
@@ -342,7 +343,6 @@ struct sc16is7xx_port {
 	unsigned char			buf[SC16IS7XX_FIFO_SIZE];
 	struct kthread_worker		kworker;
 	struct task_struct		*kworker_task;
-	struct mutex			efr_lock;
 	struct sc16is7xx_one		p[];
 };
 
@@ -494,7 +494,6 @@ static bool sc16is7xx_regmap_precious(struct device *dev, unsigned int reg)
 
 static int sc16is7xx_set_baud(struct uart_port *port, int baud)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	u8 lcr;
 	u8 prescaler = 0;
@@ -518,7 +517,7 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
 	 * because the bulk of the interrupt processing is run as a workqueue
 	 * job in thread context.
 	 */
-	mutex_lock(&s->efr_lock);
+	mutex_lock(&one->efr_lock);
 
 	lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG);
 
@@ -537,7 +536,7 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
 	/* Put LCR back to the normal mode */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
 
-	mutex_unlock(&s->efr_lock);
+	mutex_unlock(&one->efr_lock);
 
 	sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
 			      SC16IS7XX_MCR_CLKSEL_BIT,
@@ -705,11 +704,10 @@ static unsigned int sc16is7xx_get_hwmctrl(struct uart_port *port)
 static void sc16is7xx_update_mlines(struct sc16is7xx_one *one)
 {
 	struct uart_port *port = &one->port;
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	unsigned long flags;
 	unsigned int status, changed;
 
-	lockdep_assert_held_once(&s->efr_lock);
+	lockdep_assert_held_once(&one->efr_lock);
 
 	status = sc16is7xx_get_hwmctrl(port);
 	changed = status ^ one->old_mctrl;
@@ -735,15 +733,20 @@ static void sc16is7xx_update_mlines(struct sc16is7xx_one *one)
 
 static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 {
+	bool rc = true;
 	struct uart_port *port = &s->p[portno].port;
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+	mutex_lock(&one->efr_lock);
 
 	do {
 		unsigned int iir, rxlen;
-		struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
 		iir = sc16is7xx_port_read(port, SC16IS7XX_IIR_REG);
-		if (iir & SC16IS7XX_IIR_NO_INT_BIT)
-			return false;
+		if (iir & SC16IS7XX_IIR_NO_INT_BIT) {
+			rc = false;
+			goto out_port_irq;
+		}
 
 		iir &= SC16IS7XX_IIR_ID_MASK;
 
@@ -783,15 +786,17 @@ static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 			break;
 		}
 	} while (0);
-	return true;
+
+out_port_irq:
+	mutex_unlock(&one->efr_lock);
+
+	return rc;
 }
 
 static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
 {
 	struct sc16is7xx_port *s = (struct sc16is7xx_port *)dev_id;
 
-	mutex_lock(&s->efr_lock);
-
 	while (1) {
 		bool keep_polling = false;
 		int i;
@@ -802,24 +807,22 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
 			break;
 	}
 
-	mutex_unlock(&s->efr_lock);
-
 	return IRQ_HANDLED;
 }
 
 static void sc16is7xx_tx_proc(struct kthread_work *ws)
 {
 	struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port);
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	unsigned long flags;
 
 	if ((port->rs485.flags & SER_RS485_ENABLED) &&
 	    (port->rs485.delay_rts_before_send > 0))
 		msleep(port->rs485.delay_rts_before_send);
 
-	mutex_lock(&s->efr_lock);
+	mutex_lock(&one->efr_lock);
 	sc16is7xx_handle_tx(port);
-	mutex_unlock(&s->efr_lock);
+	mutex_unlock(&one->efr_lock);
 
 	uart_port_lock_irqsave(port, &flags);
 	sc16is7xx_ier_set(port, SC16IS7XX_IER_THRI_BIT);
@@ -926,9 +929,9 @@ static void sc16is7xx_ms_proc(struct kthread_work *ws)
 	struct sc16is7xx_port *s = dev_get_drvdata(one->port.dev);
 
 	if (one->port.state) {
-		mutex_lock(&s->efr_lock);
+		mutex_lock(&one->efr_lock);
 		sc16is7xx_update_mlines(one);
-		mutex_unlock(&s->efr_lock);
+		mutex_unlock(&one->efr_lock);
 
 		kthread_queue_delayed_work(&s->kworker, &one->ms_work, HZ);
 	}
@@ -1012,7 +1015,6 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 				  struct ktermios *termios,
 				  const struct ktermios *old)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	unsigned int lcr, flow = 0;
 	int baud;
@@ -1071,7 +1073,7 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 		port->ignore_status_mask |= SC16IS7XX_LSR_BRK_ERROR_MASK;
 
 	/* As above, claim the mutex while accessing the EFR. */
-	mutex_lock(&s->efr_lock);
+	mutex_lock(&one->efr_lock);
 
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
 			     SC16IS7XX_LCR_CONF_MODE_B);
@@ -1101,7 +1103,7 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 	/* Update LCR register */
 	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
 
-	mutex_unlock(&s->efr_lock);
+	mutex_unlock(&one->efr_lock);
 
 	/* Get baud rate generator configuration */
 	baud = uart_get_baud_rate(port, termios, old,
@@ -1535,7 +1537,6 @@ static int sc16is7xx_probe(struct device *dev,
 
 	s->devtype = devtype;
 	dev_set_drvdata(dev, s);
-	mutex_init(&s->efr_lock);
 
 	kthread_init_worker(&s->kworker);
 	s->kworker_task = kthread_run(kthread_worker_fn, &s->kworker,
@@ -1578,6 +1579,8 @@ static int sc16is7xx_probe(struct device *dev,
 			goto out_ports;
 		}
 
+		mutex_init(&s->p[i].efr_lock);
+
 		ret = uart_get_rs485_mode(&s->p[i].port);
 		if (ret)
 			goto out_ports;