This is a note to let you know that I've just added the patch titled

serial: sc16is7xx: convert from _raw_ to _noinc_ regmap functions for

to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From dbf4ab821804df071c8b566d9813083125e6d97b Mon Sep 17 00:00:00 2001 From: Hugo Villeneuve hvilleneuve@dimonoff.com Date: Mon, 11 Dec 2023 12:13:52 -0500 Subject: serial: sc16is7xx: convert from _raw_ to _noinc_ regmap functions for FIFO

The SC16IS7XX IC supports a burst mode to access the FIFOs where the initial register address is sent ($00), followed by all the FIFO data without having to resend the register address each time. In this mode, the IC doesn't increment the register address for each R/W byte.

The regmap_raw_read() and regmap_raw_write() are functions which can perform IO over multiple registers. They are currently used to read/write from/to the FIFO, and although they operate correctly in this burst mode on the SPI bus, they would corrupt the regmap cache if it was not disabled manually. The reason is that when the R/W size is more than 1 byte, these functions assume that the register address is incremented and handle the cache accordingly.

Convert FIFO R/W functions to use the regmap _noinc_ versions in order to remove the manual cache control which was a workaround when using the _raw_ versions. FIFO registers are properly declared as volatile so cache will not be used/updated for FIFO accesses.

Fixes: dfeae619d781 ("serial: sc16is7xx") Cc: stable@vger.kernel.org Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Link: https://lore.kernel.org/r/20231211171353.2901416-6-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/sc16is7xx.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 0bda9b74d096..7e4b9b52841d 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -381,9 +381,7 @@ static void sc16is7xx_fifo_read(struct uart_port *port, unsigned int rxlen) struct sc16is7xx_port *s = dev_get_drvdata(port->dev); struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);

- regcache_cache_bypass(one->regmap, true); - regmap_raw_read(one->regmap, SC16IS7XX_RHR_REG, s->buf, rxlen); - regcache_cache_bypass(one->regmap, false); + regmap_noinc_read(one->regmap, SC16IS7XX_RHR_REG, s->buf, rxlen); }

static void sc16is7xx_fifo_write(struct uart_port *port, u8 to_send) @@ -398,9 +396,7 @@ static void sc16is7xx_fifo_write(struct uart_port *port, u8 to_send) if (unlikely(!to_send)) return;

- regcache_cache_bypass(one->regmap, true); - regmap_raw_write(one->regmap, SC16IS7XX_THR_REG, s->buf, to_send); - regcache_cache_bypass(one->regmap, false); + regmap_noinc_write(one->regmap, SC16IS7XX_THR_REG, s->buf, to_send); }

static void sc16is7xx_port_update(struct uart_port *port, u8 reg, @@ -492,6 +488,11 @@ static bool sc16is7xx_regmap_precious(struct device *dev, unsigned int reg) return false; }

+static bool sc16is7xx_regmap_noinc(struct device *dev, unsigned int reg) +{ + return reg == SC16IS7XX_RHR_REG; +} + static int sc16is7xx_set_baud(struct uart_port *port, int baud) { struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); @@ -1709,6 +1710,10 @@ static struct regmap_config regcfg = { .cache_type = REGCACHE_RBTREE, .volatile_reg = sc16is7xx_regmap_volatile, .precious_reg = sc16is7xx_regmap_precious, + .writeable_noinc_reg = sc16is7xx_regmap_noinc, + .readable_noinc_reg = sc16is7xx_regmap_noinc, + .max_raw_read = SC16IS7XX_FIFO_SIZE, + .max_raw_write = SC16IS7XX_FIFO_SIZE, .max_register = SC16IS7XX_EFCR_REG, };