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-testing 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 be merged to the tty-next branch sometime soon,
after it passes testing, and the merge window is open.
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@xxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231211171353.2901416-6-hugo@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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,
};
--
2.43.0
