Re: [PATCH v3 3/3] serial: sc16is7xx: add support for EXAR XR20M1172 UART

From: Jiri Slaby
Date: Fri Apr 19 2024 - 02:45:21 EST


On 18. 04. 24, 19:06, Konstantin Pugin wrote:
From: Konstantin Pugin <ria.freelander@xxxxxxxxx>

XR20M1172 register set is mostly compatible with SC16IS762, but it has
a support for additional division rates of UART with special DLD register.
So, add handling this register by appropriate devicetree bindings.

Reviewed-by: Vladimir Zapolskiy <vz@xxxxxxxxx>
Signed-off-by: Konstantin Pugin <ria.freelander@xxxxxxxxx>
---
drivers/tty/serial/sc16is7xx.c | 55 +++++++++++++++++++++++++++++++---
1 file changed, 51 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index a300eebf1401..59376c637467 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
..
@@ -218,6 +219,20 @@
#define SC16IS7XX_TCR_RX_HALT(words) ((((words) / 4) & 0x0f) << 0)
#define SC16IS7XX_TCR_RX_RESUME(words) ((((words) / 4) & 0x0f) << 4)
+/*
+ * Divisor Fractional Register bits (EXAR extension)
+ * EXAR hardware is mostly compatible with SC16IS7XX, but supports additional feature:
+ * 4x and 8x divisor, instead of default 16x. It has a special register to program it.
+ * Bits 0 to 3 is fractional divisor, it used to set value of last 16 bits of
+ * uartclk * (16 / divisor) / baud, in case of default it will be uartclk / baud.
+ * Bits 4 and 5 used as switches, and should not be set to 1 simultaneously.
+ */
+
+#define XR20M117X_DLD_16X 0
+#define XR20M117X_DLD_DIV(m) ((m) & GENMASK(3, 0))

Again, why not set this up as a mask and use FIELD_PREP?

Could you stop submitting this many series in such a short time lapse? It makes reviewing a major PITA.

--
js
suse labs