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Date: Mon, 2 Feb 2015 18:28:12 +0300
From: Max Filippov <jcmvbkbc@...il.com>
To: Peter Korsgaard <jacmet@...site.dk>
Cc: Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org, Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH v2 1/2] i2c: i2c-ocores: fix clock-frequency binding usage
clock-frequency property is meant to control the bus frequency for i2c bus
drivers, but it was incorrectly used to specify i2c controller input clock
frequency.
Introduce new attribute, opencores,ip-clock-frequency, that specifies i2c
controller clock frequency and make clock-frequency attribute compatible
with other i2c drivers. Maintain backwards compatibility in case
opencores,ip-clock-frequency attribute is missing.
Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
Changes v1->v2:
- new patch
.../devicetree/bindings/i2c/i2c-ocores.txt | 18 ++++++-
drivers/i2c/busses/i2c-ocores.c | 55 +++++++++++++++++-----
2 files changed, 58 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
index 1637c29..5bef3ad 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
@@ -4,15 +4,29 @@ Required properties:
- compatible : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
- reg : bus address start and address range size of device
- interrupts : interrupt number
-- clock-frequency : frequency of bus clock in Hz
+- opencores,ip-clock-frequency: frequency of the controller clock in Hz;
+ see the note below
- #address-cells : should be <1>
- #size-cells : should be <0>
Optional properties:
+- clock-frequency : frequency of bus clock in Hz; see the note below.
+ Defaults to 100 KHz when the property is not specified
- reg-shift : device register offsets are shifted by this value
- reg-io-width : io register width in bytes (1, 2 or 4)
- regstep : deprecated, use reg-shift above
+Note
+clock-frequency property is meant to control the bus frequency for i2c bus
+drivers, but it was incorrectly used to specify i2c controller input clock
+frequency. So the following rules are set to fix this situation:
+- if clock-frequency is present and opencores,ip-clock-frequency is not,
+ then clock-frequency specifies i2c controller clock frequency. This is
+ to keep backwards compatibility with setups using old DTB. i2c bus
+ frequency is fixed at 100 KHz.
+- if opencores,ip-clock-frequency is present it specifies i2c controller
+ clock frequency. clock-frequency property specifies i2c bus frequency.
+
Example:
i2c0: ocores@...00000 {
@@ -21,7 +35,7 @@ Example:
compatible = "opencores,i2c-ocores";
reg = <0xa0000000 0x8>;
interrupts = <10>;
- clock-frequency = <20000000>;
+ opencores,ip-clock-frequency = <20000000>;
reg-shift = <0>; /* 8 bit registers */
reg-io-width = <1>; /* 8 bit read/write */
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index 2a4fe0b..bff99e3 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -35,7 +35,8 @@ struct ocores_i2c {
int pos;
int nmsgs;
int state; /* see STATE_ */
- int clock_khz;
+ int ip_clock_khz;
+ int bus_clock_khz;
void (*setreg)(struct ocores_i2c *i2c, int reg, u8 value);
u8 (*getreg)(struct ocores_i2c *i2c, int reg);
};
@@ -215,21 +216,34 @@ static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
return -ETIMEDOUT;
}
-static void ocores_init(struct ocores_i2c *i2c)
+static int ocores_init(struct device *dev, struct ocores_i2c *i2c)
{
int prescale;
+ int diff;
u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
/* make sure the device is disabled */
oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
- prescale = (i2c->clock_khz / (5*100)) - 1;
+ prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1;
+ prescale = clamp(prescale, 0, 0xffff);
+
+ diff = i2c->ip_clock_khz / (5 * (prescale + 1)) - i2c->bus_clock_khz;
+ if (abs(diff) > i2c->bus_clock_khz / 10) {
+ dev_err(dev,
+ "Unsupported clock settings: core: %d KHz, bus: %d KHz\n",
+ i2c->ip_clock_khz, i2c->bus_clock_khz);
+ return -EINVAL;
+ }
+
oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
/* Init the device */
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
+
+ return 0;
}
@@ -304,6 +318,8 @@ static int ocores_i2c_of_probe(struct platform_device *pdev,
struct device_node *np = pdev->dev.of_node;
const struct of_device_id *match;
u32 val;
+ u32 clock_frequency;
+ bool clock_frequency_present;
if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) {
/* no 'reg-shift', check for deprecated 'regstep' */
@@ -319,12 +335,24 @@ static int ocores_i2c_of_probe(struct platform_device *pdev,
}
}
- if (of_property_read_u32(np, "clock-frequency", &val)) {
- dev_err(&pdev->dev,
- "Missing required parameter 'clock-frequency'\n");
- return -ENODEV;
+ clock_frequency_present = !of_property_read_u32(np, "clock-frequency",
+ &clock_frequency);
+ i2c->bus_clock_khz = 100;
+
+ if (of_property_read_u32(np, "opencores,ip-clock-frequency", &val)) {
+ if (!clock_frequency_present) {
+ dev_err(&pdev->dev,
+ "Missing required parameter 'opencores,ip-clock-frequency'\n");
+ return -ENODEV;
+ }
+ i2c->ip_clock_khz = clock_frequency / 1000;
+ dev_warn(&pdev->dev,
+ "Deprecated usage of the 'clock-frequency' property, please update to 'opencores,ip-clock-frequency'\n");
+ } else {
+ i2c->ip_clock_khz = val / 1000;
+ if (clock_frequency_present)
+ i2c->bus_clock_khz = clock_frequency / 1000;
}
- i2c->clock_khz = val / 1000;
of_property_read_u32(pdev->dev.of_node, "reg-io-width",
&i2c->reg_io_width);
@@ -368,7 +396,8 @@ static int ocores_i2c_probe(struct platform_device *pdev)
if (pdata) {
i2c->reg_shift = pdata->reg_shift;
i2c->reg_io_width = pdata->reg_io_width;
- i2c->clock_khz = pdata->clock_khz;
+ i2c->ip_clock_khz = pdata->clock_khz;
+ i2c->bus_clock_khz = 100;
} else {
ret = ocores_i2c_of_probe(pdev, i2c);
if (ret)
@@ -402,7 +431,9 @@ static int ocores_i2c_probe(struct platform_device *pdev)
}
}
- ocores_init(i2c);
+ ret = ocores_init(&pdev->dev, i2c);
+ if (ret)
+ return ret;
init_waitqueue_head(&i2c->wait);
ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
@@ -465,9 +496,7 @@ static int ocores_i2c_resume(struct device *dev)
{
struct ocores_i2c *i2c = dev_get_drvdata(dev);
- ocores_init(i2c);
-
- return 0;
+ return ocores_init(dev, i2c);
}
static SIMPLE_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume);
--
1.8.1.4
--
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