serial: max3100: Enable TIOCM_LOOP

Enable or disable loopback at run-time.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240409144721.638326-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
index 75e96ff745715429663681a38b0c9f4bdced307a..4a4343e7b1fa1fb15340a007e35d6b3d67394dd8 100644 (file)
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -32,14 +32,12 @@
 
 /**
  * struct plat_max3100 - MAX3100 SPI UART platform data
- * @loopback:            force MAX3100 in loopback
  * @crystal:             1 for 3.6864 Mhz, 0 for 1.8432
  *
  * You should use this structure in your machine description to specify
  * how the MAX3100 is connected.
  */
 struct plat_max3100 {
-       int loopback;
        int crystal;
 };
 
@@ -109,6 +107,7 @@ struct max3100_port {
 
        int minor;              /* minor number */
        int crystal;            /* 1 if 3.6864Mhz crystal 0 for 1.8432 */
+       int loopback_commit;    /* need to change loopback */
        int loopback;           /* 1 if we are in loopback mode */
 
        /* for handling irqs: need workqueue since we do spi_sync */
@@ -241,9 +240,9 @@ static void max3100_work(struct work_struct *w)
        struct max3100_port *s = container_of(w, struct max3100_port, work);
        struct tty_port *tport = &s->port.state->port;
        unsigned char ch;
+       int conf, cconf, cloopback, crts;
        int rxchars;
        u16 tx, rx;
-       int conf, cconf, crts;
 
        dev_dbg(&s->spi->dev, "%s\n", __func__);
 
@@ -253,11 +252,15 @@ static void max3100_work(struct work_struct *w)
                conf = s->conf;
                cconf = s->conf_commit;
                s->conf_commit = 0;
+               cloopback = s->loopback_commit;
+               s->loopback_commit = 0;
                crts = s->rts_commit;
                s->rts_commit = 0;
                spin_unlock(&s->conf_lock);
                if (cconf)
                        max3100_sr(s, MAX3100_WC | conf, &rx);
+               if (cloopback)
+                       max3100_sr(s, 0x4001, &rx);
                if (crts) {
                        max3100_sr(s, MAX3100_WD | MAX3100_TE |
                                   (s->rts ? MAX3100_RTS : 0), &rx);
@@ -395,18 +398,24 @@ static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
        struct max3100_port *s = container_of(port,
                                              struct max3100_port,
                                              port);
-       int rts;
+       int loopback, rts;
 
        dev_dbg(&s->spi->dev, "%s\n", __func__);
 
+       loopback = (mctrl & TIOCM_LOOP) > 0;
        rts = (mctrl & TIOCM_RTS) > 0;
 
        spin_lock(&s->conf_lock);
+       if (s->loopback != loopback) {
+               s->loopback = loopback;
+               s->loopback_commit = 1;
+       }
        if (s->rts != rts) {
                s->rts = rts;
                s->rts_commit = 1;
-               max3100_dowork(s);
        }
+       if (s->loopback_commit || s->rts_commit)
+               max3100_dowork(s);
        spin_unlock(&s->conf_lock);
 }
 
@@ -593,12 +602,6 @@ static int max3100_startup(struct uart_port *port)
                return -EBUSY;
        }
 
-       if (s->loopback) {
-               u16 tx, rx;
-               tx = 0x4001;
-               max3100_sr(s, tx, &rx);
-       }
-
        s->conf_commit = 1;
        max3100_dowork(s);
        /* wait for clock to settle */
@@ -754,7 +757,6 @@ static int max3100_probe(struct spi_device *spi)
        spi_set_drvdata(spi, max3100s[i]);
        pdata = dev_get_platdata(&spi->dev);
        max3100s[i]->crystal = pdata->crystal;
-       max3100s[i]->loopback = pdata->loopback;
        max3100s[i]->minor = i;
        timer_setup(&max3100s[i]->timer, max3100_timeout, 0);