serial: max3100: Remove custom HW shutdown support

While there is no user of this callback in the kernel, it also breaks
the relationship in the driver model. The correct implementation should
be done via GPIO or regulator framework.

Remove custom HW shutdown support for good and, if needed, we will
implement it correctly later on.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240402195306.269276-6-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/max3100.c

@@ -34,8 +34,6 @@
  * struct plat_max3100 - MAX3100 SPI UART platform data
  * @loopback:            force MAX3100 in loopback
  * @crystal:             1 for 3.6864 Mhz, 0 for 1.8432
- * @max3100_hw_suspend:  MAX3100 has a shutdown pin. This is a hook
- *                       called on suspend and resume to activate it.
  * @poll_time:           poll time for CTS signal in ms, 0 disables (so no hw
  *                       flow ctrl is possible but you have less CPU usage)
  *
@@ -45,7 +43,6 @@
 struct plat_max3100 {
 	int loopback;
 	int crystal;
-	void (*max3100_hw_suspend) (int suspend);
 	int poll_time;
 };
 
@@ -125,9 +122,6 @@ struct max3100_port {
 	/* need to know we are suspending to avoid deadlock on workqueue */
 	int suspending;
 
-	/* hook for suspending MAX3100 via dedicated pin */
-	void (*max3100_hw_suspend) (int suspend);
-
 	/* poll time (in ms) for ctrl lines */
 	int poll_time;
 	/* and its timer */
@@ -553,6 +547,7 @@ static void max3100_shutdown(struct uart_port *port)
 	struct max3100_port *s = container_of(port,
 					      struct max3100_port,
 					      port);
+	u16 rx;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -572,14 +567,7 @@ static void max3100_shutdown(struct uart_port *port)
 		free_irq(s->irq, s);
 
 	/* set shutdown mode to save power */
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(1);
-	else  {
-		u16 tx, rx;
-
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(s, tx, &rx);
-	}
+	max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
 }
 
 static int max3100_startup(struct uart_port *port)
@@ -625,8 +613,6 @@ static int max3100_startup(struct uart_port *port)
 		max3100_sr(s, tx, &rx);
 	}
 
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(0);
 	s->conf_commit = 1;
 	max3100_dowork(s);
 	/* wait for clock to settle */
@@ -745,7 +731,7 @@ static int max3100_probe(struct spi_device *spi)
 {
 	int i, retval;
 	struct plat_max3100 *pdata;
-	u16 tx, rx;
+	u16 rx;
 
 	mutex_lock(&max3100s_lock);
 
@@ -786,7 +772,6 @@ static int max3100_probe(struct spi_device *spi)
 	max3100s[i]->poll_time = msecs_to_jiffies(pdata->poll_time);
 	if (pdata->poll_time > 0 && max3100s[i]->poll_time == 0)
 		max3100s[i]->poll_time = 1;
-	max3100s[i]->max3100_hw_suspend = pdata->max3100_hw_suspend;
 	max3100s[i]->minor = i;
 	timer_setup(&max3100s[i]->timer, max3100_timeout, 0);
 
@@ -806,12 +791,7 @@ static int max3100_probe(struct spi_device *spi)
 			 i, retval);
 
 	/* set shutdown mode to save power. Will be woken-up on open */
-	if (max3100s[i]->max3100_hw_suspend)
-		max3100s[i]->max3100_hw_suspend(1);
-	else {
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(max3100s[i], tx, &rx);
-	}
+	max3100_sr(max3100s[i], MAX3100_WC | MAX3100_SHDN, &rx);
 	mutex_unlock(&max3100s_lock);
 	return 0;
 }
@@ -853,6 +833,7 @@ static void max3100_remove(struct spi_device *spi)
 static int max3100_suspend(struct device *dev)
 {
 	struct max3100_port *s = dev_get_drvdata(dev);
+	u16 rx;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -861,15 +842,8 @@ static int max3100_suspend(struct device *dev)
 	s->suspending = 1;
 	uart_suspend_port(&max3100_uart_driver, &s->port);
 
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(1);
-	else {
-		/* no HW suspend, so do SW one */
-		u16 tx, rx;
-
-		tx = MAX3100_WC | MAX3100_SHDN;
-		max3100_sr(s, tx, &rx);
-	}
+	/* no HW suspend, so do SW one */
+	max3100_sr(s, MAX3100_WC | MAX3100_SHDN, &rx);
 	return 0;
 }
 
@@ -879,8 +853,6 @@ static int max3100_resume(struct device *dev)
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 
-	if (s->max3100_hw_suspend)
-		s->max3100_hw_suspend(0);
 	uart_resume_port(&max3100_uart_driver, &s->port);
 	s->suspending = 0;