diff options
| -rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 18 | ||||
| -rw-r--r-- | 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 1637c298a1b3..5bef3adf2c35 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@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 */ diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c index 7249b5b1e5d0..6cbbb134cfb7 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); |