6.6-stable review patch. If anyone has any objections, please let me know.
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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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/sc16is7xx.c | 106 ++++++++++++++++++++++------------------- 1 file changed, 57 insertions(+), 49 deletions(-)
--- 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_ 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 uar 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, @@ -579,7 +596,8 @@ static int sc16is7xx_set_baud(struct uar
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);
@@ -589,7 +607,7 @@ static int sc16is7xx_set_baud(struct uar 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); @@ -1070,17 +1088,7 @@ static void sc16is7xx_set_termios(struct 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 | @@ -1092,16 +1100,16 @@ static void sc16is7xx_set_termios(struct 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,