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From: Heiner Kallweit <hkallweit1@gmail.com>
To: Wolfram Sang <wsa@the-dreams.de>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>
Cc: "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	linux-amlogic@lists.infradead.org
Subject: [PATCH v5 05/10] i2c: meson: use full 12 bits for clock divider
Date: Sat, 25 Mar 2017 14:07:57 +0100	[thread overview]
Message-ID: <8b913c11-e51e-11aa-4525-fc3c8c4d972e@gmail.com> (raw)
In-Reply-To: <645519b8-93e6-57b1-ae8f-7804c6beb9b1@gmail.com>

The clock divider has 12 bits, splitted into a 10 bit field and a
2 bit field. The extra 2 bits aren't used currently.

Change this to use the full 12 bits and warn if the requested
frequency is too low.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
---
v2:
- added Acked-by
v3:
- changed order of patches
v4:
- no changes
v5:
- change WARN_ON to dev_err
---
 drivers/i2c/busses/i2c-meson.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index ac0ac82d..25ea05fc 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -35,7 +35,9 @@
 #define REG_CTRL_STATUS		BIT(2)
 #define REG_CTRL_ERROR		BIT(3)
 #define REG_CTRL_CLKDIV_SHIFT	12
-#define REG_CTRL_CLKDIV_MASK	((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
+#define REG_CTRL_CLKDIV_MASK	GENMASK(21, 12)
+#define REG_CTRL_CLKDIVEXT_SHIFT 28
+#define REG_CTRL_CLKDIVEXT_MASK	GENMASK(29, 28)
 
 #define I2C_TIMEOUT_MS		500
 
@@ -134,8 +136,18 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 	unsigned int div;
 
 	div = DIV_ROUND_UP(clk_rate, freq * 4);
+
+	/* clock divider has 12 bits */
+	if (div >= (1 << 12)) {
+		dev_err(i2c->dev, "requested bus frequency too low\n");
+		div = (1 << 12) - 1;
+	}
+
 	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
-			   div << REG_CTRL_CLKDIV_SHIFT);
+			   (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
+
+	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
+			   (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 
 	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 		clk_rate, freq, div);
-- 
2.12.0

WARNING: multiple messages have this Message-ID (diff)
From: hkallweit1@gmail.com (Heiner Kallweit)
To: linus-amlogic@lists.infradead.org
Subject: [PATCH v5 05/10] i2c: meson: use full 12 bits for clock divider
Date: Sat, 25 Mar 2017 14:07:57 +0100	[thread overview]
Message-ID: <8b913c11-e51e-11aa-4525-fc3c8c4d972e@gmail.com> (raw)
In-Reply-To: <645519b8-93e6-57b1-ae8f-7804c6beb9b1@gmail.com>

The clock divider has 12 bits, splitted into a 10 bit field and a
2 bit field. The extra 2 bits aren't used currently.

Change this to use the full 12 bits and warn if the requested
frequency is too low.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
---
v2:
- added Acked-by
v3:
- changed order of patches
v4:
- no changes
v5:
- change WARN_ON to dev_err
---
 drivers/i2c/busses/i2c-meson.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index ac0ac82d..25ea05fc 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -35,7 +35,9 @@
 #define REG_CTRL_STATUS		BIT(2)
 #define REG_CTRL_ERROR		BIT(3)
 #define REG_CTRL_CLKDIV_SHIFT	12
-#define REG_CTRL_CLKDIV_MASK	((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
+#define REG_CTRL_CLKDIV_MASK	GENMASK(21, 12)
+#define REG_CTRL_CLKDIVEXT_SHIFT 28
+#define REG_CTRL_CLKDIVEXT_MASK	GENMASK(29, 28)
 
 #define I2C_TIMEOUT_MS		500
 
@@ -134,8 +136,18 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 	unsigned int div;
 
 	div = DIV_ROUND_UP(clk_rate, freq * 4);
+
+	/* clock divider has 12 bits */
+	if (div >= (1 << 12)) {
+		dev_err(i2c->dev, "requested bus frequency too low\n");
+		div = (1 << 12) - 1;
+	}
+
 	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
-			   div << REG_CTRL_CLKDIV_SHIFT);
+			   (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
+
+	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
+			   (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 
 	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 		clk_rate, freq, div);
-- 
2.12.0

  parent reply	other threads:[~2017-03-25 13:14 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-25 12:57 [PATCH v5 00/10] i2c: meson: series with improvements Heiner Kallweit
2017-03-25 12:57 ` Heiner Kallweit
2017-03-25 12:58 ` [PATCH v5 01/10] i2c: meson: use min instead of min_t where min_t isn't needed Heiner Kallweit
2017-03-25 12:58   ` Heiner Kallweit
2017-03-25 13:01 ` [PATCH v5 02/10] i2c: meson: remove member irq from struct meson_i2c Heiner Kallweit
2017-03-25 13:01   ` Heiner Kallweit
2017-03-25 13:04 ` [PATCH v5 03/10] i2c: meson: set clock divider in probe instead of setting it for each transfer Heiner Kallweit
2017-03-25 13:04   ` Heiner Kallweit
2017-03-25 13:06 ` [PATCH v5 04/10] i2c: meson: use i2c core for DT clock-frequency parsing Heiner Kallweit
2017-03-25 13:06   ` Heiner Kallweit
2017-03-25 13:07 ` Heiner Kallweit [this message]
2017-03-25 13:07   ` [PATCH v5 05/10] i2c: meson: use full 12 bits for clock divider Heiner Kallweit
2017-03-25 13:09 ` [PATCH v5 06/10] i2c: meson: remove variable count from meson_i2c_xfer Heiner Kallweit
2017-03-25 13:09   ` Heiner Kallweit
2017-03-25 13:10 ` [PATCH v5 07/10] i2c: meson: improve interrupt handler and detect spurious interrupts Heiner Kallweit
2017-03-25 13:10   ` Heiner Kallweit
2017-03-25 13:11 ` [PATCH v5 08/10] i2c: meson: don't create separate token chain just for the stop command Heiner Kallweit
2017-03-25 13:11   ` Heiner Kallweit
2017-03-25 13:12 ` [PATCH v5 09/10] i2c: meson: remove meson_i2c_write_tokens Heiner Kallweit
2017-03-25 13:12   ` Heiner Kallweit
2017-03-25 13:14 ` [PATCH v5 10/10] i2c: meson: improve and simplify interrupt handler Heiner Kallweit
2017-03-25 13:14   ` Heiner Kallweit
2017-03-30 15:56 ` [PATCH v5 00/10] i2c: meson: series with improvements Wolfram Sang
2017-03-30 15:56   ` Wolfram Sang

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