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i2c: ocores: fix clock-frequency binding usage

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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@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Max Filippov 2015-02-02 18:28:12 +03:00 committed by Wolfram Sang
parent 8c340f6090
commit 3a33a85401
2 changed files with 58 additions and 15 deletions
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18
Documentation/devicetree/bindings/i2c/i2c-ocores.txt
View File

@ -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@a0000000 {
@ -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 */

55
drivers/i2c/busses/i2c-ocores.c
View File

@ -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);