* [PATCH 6.1.y 2/4] serial: sc16is7xx: reorder code to remove prototype declarations
2025-10-27 18:53 ` [PATCH 6.1.y 1/4] serial: sc16is7xx: remove unused to_sc16is7xx_port macro Sasha Levin
@ 2025-10-27 18:53 ` Sasha Levin
2025-10-27 18:53 ` [PATCH 6.1.y 3/4] serial: sc16is7xx: refactor EFR lock Sasha Levin
2025-10-27 18:53 ` [PATCH 6.1.y 4/4] serial: sc16is7xx: remove useless enable of enhanced features Sasha Levin
2 siblings, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2025-10-27 18:53 UTC (permalink / raw)
To: stable; +Cc: Hugo Villeneuve, Andy Shevchenko, Greg Kroah-Hartman, Sasha Levin
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
[ Upstream commit 2de8a1b46756b5a79d8447f99afdfe49e914225a ]
Move/reorder some functions to remove sc16is7xx_ier_set() and
sc16is7xx_stop_tx() prototypes declarations.
No functional change.
sc16is7xx_ier_set() was introduced in
commit cc4c1d05eb10 ("sc16is7xx: Properly resume TX after stop").
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231221231823.2327894-16-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 1c05bf6c0262 ("serial: sc16is7xx: remove useless enable of enhanced features")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/sc16is7xx.c | 75 ++++++++++++++++------------------
1 file changed, 36 insertions(+), 39 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index a187ae217fc4c..f87fcde9a3d49 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -355,9 +355,6 @@ static struct uart_driver sc16is7xx_uart = {
.nr = SC16IS7XX_MAX_DEVS,
};
-static void sc16is7xx_ier_set(struct uart_port *port, u8 bit);
-static void sc16is7xx_stop_tx(struct uart_port *port);
-
#define to_sc16is7xx_one(p,e) ((container_of((p), struct sc16is7xx_one, e)))
static u8 sc16is7xx_port_read(struct uart_port *port, u8 reg)
@@ -415,6 +412,42 @@ static void sc16is7xx_power(struct uart_port *port, int on)
on ? 0 : SC16IS7XX_IER_SLEEP_BIT);
}
+static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)
+{
+ struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+ struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+ lockdep_assert_held_once(&port->lock);
+
+ one->config.flags |= SC16IS7XX_RECONF_IER;
+ one->config.ier_mask |= bit;
+ one->config.ier_val &= ~bit;
+ kthread_queue_work(&s->kworker, &one->reg_work);
+}
+
+static void sc16is7xx_ier_set(struct uart_port *port, u8 bit)
+{
+ struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+ struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+ lockdep_assert_held_once(&port->lock);
+
+ one->config.flags |= SC16IS7XX_RECONF_IER;
+ one->config.ier_mask |= bit;
+ one->config.ier_val |= bit;
+ kthread_queue_work(&s->kworker, &one->reg_work);
+}
+
+static void sc16is7xx_stop_tx(struct uart_port *port)
+{
+ sc16is7xx_ier_clear(port, SC16IS7XX_IER_THRI_BIT);
+}
+
+static void sc16is7xx_stop_rx(struct uart_port *port)
+{
+ sc16is7xx_ier_clear(port, SC16IS7XX_IER_RDI_BIT);
+}
+
static const struct sc16is7xx_devtype sc16is74x_devtype = {
.name = "SC16IS74X",
.nr_gpio = 0,
@@ -891,42 +924,6 @@ static void sc16is7xx_reg_proc(struct kthread_work *ws)
sc16is7xx_reconf_rs485(&one->port);
}
-static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)
-{
- struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
- struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
-
- lockdep_assert_held_once(&port->lock);
-
- one->config.flags |= SC16IS7XX_RECONF_IER;
- one->config.ier_mask |= bit;
- one->config.ier_val &= ~bit;
- kthread_queue_work(&s->kworker, &one->reg_work);
-}
-
-static void sc16is7xx_ier_set(struct uart_port *port, u8 bit)
-{
- struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
- struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
-
- lockdep_assert_held_once(&port->lock);
-
- one->config.flags |= SC16IS7XX_RECONF_IER;
- one->config.ier_mask |= bit;
- one->config.ier_val |= bit;
- kthread_queue_work(&s->kworker, &one->reg_work);
-}
-
-static void sc16is7xx_stop_tx(struct uart_port *port)
-{
- sc16is7xx_ier_clear(port, SC16IS7XX_IER_THRI_BIT);
-}
-
-static void sc16is7xx_stop_rx(struct uart_port *port)
-{
- sc16is7xx_ier_clear(port, SC16IS7XX_IER_RDI_BIT);
-}
-
static void sc16is7xx_ms_proc(struct kthread_work *ws)
{
struct sc16is7xx_one *one = to_sc16is7xx_one(ws, ms_work.work);
--
2.51.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 6.1.y 3/4] serial: sc16is7xx: refactor EFR lock
2025-10-27 18:53 ` [PATCH 6.1.y 1/4] serial: sc16is7xx: remove unused to_sc16is7xx_port macro Sasha Levin
2025-10-27 18:53 ` [PATCH 6.1.y 2/4] serial: sc16is7xx: reorder code to remove prototype declarations Sasha Levin
@ 2025-10-27 18:53 ` Sasha Levin
2025-10-27 18:53 ` [PATCH 6.1.y 4/4] serial: sc16is7xx: remove useless enable of enhanced features Sasha Levin
2 siblings, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2025-10-27 18:53 UTC (permalink / raw)
To: stable; +Cc: Hugo Villeneuve, Greg Kroah-Hartman, Sasha Levin
From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
[ Upstream commit 0c84bea0cabc4e2b98a3de88eeb4ff798931f056 ]
Move common code for EFR lock/unlock of mutex into functions for code reuse
and clarity.
With the addition of old_lcr, move irda_mode within struct sc16is7xx_one to
reduce memory usage:
Before: /* size: 752, cachelines: 12, members: 10 */
After: /* size: 744, cachelines: 12, members: 10 */
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231221231823.2327894-17-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 1c05bf6c0262 ("serial: sc16is7xx: remove useless enable of enhanced features")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/sc16is7xx.c | 106 ++++++++++++++++++---------------
1 file changed, 57 insertions(+), 49 deletions(-)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index f87fcde9a3d49..c0c2c1450e88d 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -329,8 +329,9 @@ struct sc16is7xx_one {
struct kthread_work reg_work;
struct kthread_delayed_work ms_work;
struct sc16is7xx_one_config config;
- bool irda_mode;
unsigned int old_mctrl;
+ u8 old_lcr; /* Value before EFR access. */
+ bool irda_mode;
};
struct sc16is7xx_port {
@@ -412,6 +413,49 @@ static void sc16is7xx_power(struct uart_port *port, int on)
on ? 0 : SC16IS7XX_IER_SLEEP_BIT);
}
+/*
+ * In an amazing feat of design, the Enhanced Features Register (EFR)
+ * shares the address of the Interrupt Identification Register (IIR).
+ * Access to EFR is switched on by writing a magic value (0xbf) to the
+ * Line Control Register (LCR). Any interrupt firing during this time will
+ * see the EFR where it expects the IIR to be, leading to
+ * "Unexpected interrupt" messages.
+ *
+ * Prevent this possibility by claiming a mutex while accessing the EFR,
+ * and claiming the same mutex from within the interrupt handler. This is
+ * similar to disabling the interrupt, but that doesn't work because the
+ * bulk of the interrupt processing is run as a workqueue job in thread
+ * context.
+ */
+static void sc16is7xx_efr_lock(struct uart_port *port)
+{
+ struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+ mutex_lock(&one->efr_lock);
+
+ /* Backup content of LCR. */
+ one->old_lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG);
+
+ /* Enable access to Enhanced register set */
+ sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_CONF_MODE_B);
+
+ /* Disable cache updates when writing to EFR registers */
+ regcache_cache_bypass(one->regmap, true);
+}
+
+static void sc16is7xx_efr_unlock(struct uart_port *port)
+{
+ struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+ /* Re-enable cache updates when writing to normal registers */
+ regcache_cache_bypass(one->regmap, false);
+
+ /* Restore original content of LCR */
+ sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, one->old_lcr);
+
+ mutex_unlock(&one->efr_lock);
+}
+
static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)
{
struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
@@ -538,39 +582,12 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
div /= prescaler;
}
- /* In an amazing feat of design, the Enhanced Features Register shares
- * the address of the Interrupt Identification Register, and is
- * switched in by writing a magic value (0xbf) to the Line Control
- * Register. Any interrupt firing during this time will see the EFR
- * where it expects the IIR to be, leading to "Unexpected interrupt"
- * messages.
- *
- * Prevent this possibility by claiming a mutex while accessing the
- * EFR, and claiming the same mutex from within the interrupt handler.
- * This is similar to disabling the interrupt, but that doesn't work
- * because the bulk of the interrupt processing is run as a workqueue
- * job in thread context.
- */
- mutex_lock(&one->efr_lock);
-
- lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG);
-
- /* Open the LCR divisors for configuration */
- sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
- SC16IS7XX_LCR_CONF_MODE_B);
-
/* Enable enhanced features */
- regcache_cache_bypass(one->regmap, true);
+ sc16is7xx_efr_lock(port);
sc16is7xx_port_update(port, SC16IS7XX_EFR_REG,
SC16IS7XX_EFR_ENABLE_BIT,
SC16IS7XX_EFR_ENABLE_BIT);
-
- regcache_cache_bypass(one->regmap, false);
-
- /* Put LCR back to the normal mode */
- sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
-
- mutex_unlock(&one->efr_lock);
+ sc16is7xx_efr_unlock(port);
/* If bit MCR_CLKSEL is set, the divide by 4 prescaler is activated. */
sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
@@ -580,7 +597,8 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
mutex_lock(&one->efr_lock);
- /* Open the LCR divisors for configuration */
+ /* Backup LCR and access special register set (DLL/DLH) */
+ lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG);
sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
SC16IS7XX_LCR_CONF_MODE_A);
@@ -590,7 +608,7 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
sc16is7xx_port_write(port, SC16IS7XX_DLL_REG, div % 256);
regcache_cache_bypass(one->regmap, false);
- /* Put LCR back to the normal mode */
+ /* Restore LCR and access to general register set */
sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
mutex_unlock(&one->efr_lock);
@@ -1073,17 +1091,7 @@ static void sc16is7xx_set_termios(struct uart_port *port,
if (!(termios->c_cflag & CREAD))
port->ignore_status_mask |= SC16IS7XX_LSR_BRK_ERROR_MASK;
- /* As above, claim the mutex while accessing the EFR. */
- mutex_lock(&one->efr_lock);
-
- sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
- SC16IS7XX_LCR_CONF_MODE_B);
-
/* Configure flow control */
- regcache_cache_bypass(one->regmap, true);
- sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]);
- sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]);
-
port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS);
if (termios->c_cflag & CRTSCTS) {
flow |= SC16IS7XX_EFR_AUTOCTS_BIT |
@@ -1095,16 +1103,16 @@ static void sc16is7xx_set_termios(struct uart_port *port,
if (termios->c_iflag & IXOFF)
flow |= SC16IS7XX_EFR_SWFLOW1_BIT;
- sc16is7xx_port_update(port,
- SC16IS7XX_EFR_REG,
- SC16IS7XX_EFR_FLOWCTRL_BITS,
- flow);
- regcache_cache_bypass(one->regmap, false);
-
/* Update LCR register */
sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
- mutex_unlock(&one->efr_lock);
+ /* Update EFR registers */
+ sc16is7xx_efr_lock(port);
+ sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]);
+ sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]);
+ sc16is7xx_port_update(port, SC16IS7XX_EFR_REG,
+ SC16IS7XX_EFR_FLOWCTRL_BITS, flow);
+ sc16is7xx_efr_unlock(port);
/* Get baud rate generator configuration */
baud = uart_get_baud_rate(port, termios, old,
--
2.51.0
^ permalink raw reply related [flat|nested] 5+ messages in thread