linux-kernel - [PATCH 03/10] spi: rzv2m-csi: Rework CSI_CKS

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Date:   Sat, 15 Jul 2023 02:04:00 +0100
From:   Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To:     Mark Brown <broonie@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        linux-renesas-soc@...r.kernel.org
Subject: [PATCH 03/10] spi: rzv2m-csi: Rework CSI_CKS_MAX definition

Clock "csiclk" gets divided by 2 * CSI_CLKSEL_CKS in order to generate
the serial clock (output from master), with CSI_CLKSEL_CKS ranging from
0x1 (that means "csiclk" is divided by 2) to 0x3FFF ("csiclk" is divided
by 32766). CSI_CKS_MAX is used for referring to the setting
corresponding to the maximum frequency divider.
Value 0x3FFF for CSI_CKS_MAX doesn't really means much to the reader
without an explanation and a more readable definition.

Add a comment with a meaningful description and also replace value
0x3FFF with the corresponding GENMASK, to make it very clear what the
macro means.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
---
 drivers/spi/spi-rzv2m-csi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-rzv2m-csi.c b/drivers/spi/spi-rzv2m-csi.c
index 3931045a85eb..621774949bde 100644
--- a/drivers/spi/spi-rzv2m-csi.c
+++ b/drivers/spi/spi-rzv2m-csi.c
@@ -65,7 +65,12 @@
 #define CSI_FIFO_SIZE_BYTES	32
 #define CSI_FIFO_HALF_SIZE	16
 #define CSI_EN_DIS_TIMEOUT_US	100
-#define CSI_CKS_MAX		0x3FFF
+/*
+ * Clock "csiclk" gets divided by 2 * CSI_CLKSEL_CKS in order to generate the
+ * serial clock (output from master), with CSI_CLKSEL_CKS ranging from 0x1 (that
+ * means "csiclk" is divided by 2) to 0x3FFF ("csiclk" is divided by 32766).
+ */
+#define CSI_CKS_MAX		GENMASK(13, 0)
 
 #define UNDERRUN_ERROR		BIT(0)
 #define OVERFLOW_ERROR		BIT(1)
-- 
2.34.1