linux-kernel - [PATCH v2 08/11] i2c: pasemi: Allow to configure bus frequency

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Date:   Fri,  8 Oct 2021 18:35:29 +0200
From:   Sven Peter <sven@...npeter.dev>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Olof Johansson <olof@...om.net>,
        Christian Zigotzky <chzigotzky@...osoft.de>,
        Wolfram Sang <wsa@...nel.org>
Cc:     Sven Peter <sven@...npeter.dev>, Arnd Bergmann <arnd@...db.de>,
        Hector Martin <marcan@...can.st>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Stan Skowronek <stan@...ellium.com>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 08/11] i2c: pasemi: Allow to configure bus frequency

Right now the bus frequency has always been hardcoded as
100 KHz with the specific reference clock used in the PASemi
PCI controllers. Make this configurable to prepare for the
platform driver.

Reviewed-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Sven Peter <sven@...npeter.dev>
---
v1 -> v2: no changes

 drivers/i2c/busses/i2c-pasemi-core.c | 8 +++-----
 drivers/i2c/busses/i2c-pasemi-core.h | 1 +
 drivers/i2c/busses/i2c-pasemi-pci.c  | 4 ++++
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pasemi-core.c b/drivers/i2c/busses/i2c-pasemi-core.c
index 232587c70a38..9fb8fac53f2b 100644
--- a/drivers/i2c/busses/i2c-pasemi-core.c
+++ b/drivers/i2c/busses/i2c-pasemi-core.c
@@ -39,9 +39,6 @@
 #define CTL_MTR		0x00000200
 #define CTL_CLK_M	0x000000ff
 
-#define CLK_100K_DIV	84
-#define CLK_400K_DIV	21
-
 static inline void reg_write(struct pasemi_smbus *smbus, int reg, int val)
 {
 	dev_dbg(smbus->dev, "smbus write reg %lx val %08x\n",
@@ -63,8 +60,9 @@ static inline int reg_read(struct pasemi_smbus *smbus, int reg)
 
 static void pasemi_reset(struct pasemi_smbus *smbus)
 {
-	reg_write(smbus, REG_CTL, (CTL_MTR | CTL_MRR |
-		  (CLK_100K_DIV & CTL_CLK_M)));
+	u32 val = (CTL_MTR | CTL_MRR | (smbus->clk_div & CTL_CLK_M));
+
+	reg_write(smbus, REG_CTL, val);
 }
 
 static void pasemi_smb_clear(struct pasemi_smbus *smbus)
diff --git a/drivers/i2c/busses/i2c-pasemi-core.h b/drivers/i2c/busses/i2c-pasemi-core.h
index 7acc33de6ce1..30a7990825ef 100644
--- a/drivers/i2c/busses/i2c-pasemi-core.h
+++ b/drivers/i2c/busses/i2c-pasemi-core.h
@@ -14,6 +14,7 @@ struct pasemi_smbus {
 	void __iomem		*ioaddr;
 	unsigned long		 base;
 	int			 size;
+	unsigned int		 clk_div;
 };
 
 int pasemi_i2c_common_probe(struct pasemi_smbus *smbus);
diff --git a/drivers/i2c/busses/i2c-pasemi-pci.c b/drivers/i2c/busses/i2c-pasemi-pci.c
index 644656e28012..96585bbf8c24 100644
--- a/drivers/i2c/busses/i2c-pasemi-pci.c
+++ b/drivers/i2c/busses/i2c-pasemi-pci.c
@@ -17,6 +17,9 @@
 
 #include "i2c-pasemi-core.h"
 
+#define CLK_100K_DIV	84
+#define CLK_400K_DIV	21
+
 static struct pci_driver pasemi_smb_pci_driver;
 
 static int pasemi_smb_pci_probe(struct pci_dev *dev,
@@ -35,6 +38,7 @@ static int pasemi_smb_pci_probe(struct pci_dev *dev,
 	smbus->dev = &dev->dev;
 	smbus->base = pci_resource_start(dev, 0);
 	smbus->size = pci_resource_len(dev, 0);
+	smbus->clk_div = CLK_100K_DIV;
 
 	if (!request_region(smbus->base, smbus->size,
 			    pasemi_smb_pci_driver.name)) {
-- 
2.25.1