diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-platdrv.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index 6e99d9f56dee..4c1b60539a25 100644 --- a/drivers/i2c/busses/i2c-designware-platdrv.c +++ b/drivers/i2c/busses/i2c-designware-platdrv.c @@ -53,9 +53,33 @@ static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev) } #ifdef CONFIG_ACPI +static void dw_i2c_acpi_params(struct platform_device *pdev, char method[], + u16 *hcnt, u16 *lcnt, u32 *sda_hold) +{ + struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER }; + acpi_handle handle = ACPI_HANDLE(&pdev->dev); + union acpi_object *obj; + + if (ACPI_FAILURE(acpi_evaluate_object(handle, method, NULL, &buf))) + return; + + obj = (union acpi_object *)buf.pointer; + if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 3) { + const union acpi_object *objs = obj->package.elements; + + *hcnt = (u16)objs[0].integer.value; + *lcnt = (u16)objs[1].integer.value; + if (sda_hold) + *sda_hold = (u32)objs[2].integer.value; + } + + kfree(buf.pointer); +} + static int dw_i2c_acpi_configure(struct platform_device *pdev) { struct dw_i2c_dev *dev = platform_get_drvdata(pdev); + bool fs_mode = dev->master_cfg & DW_IC_CON_SPEED_FAST; if (!ACPI_HANDLE(&pdev->dev)) return -ENODEV; @@ -63,6 +87,16 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev) dev->adapter.nr = -1; dev->tx_fifo_depth = 32; dev->rx_fifo_depth = 32; + + /* + * Try to get SDA hold time and *CNT values from an ACPI method if + * it exists for both supported speed modes. + */ + dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev->ss_lcnt, + fs_mode ? NULL : &dev->sda_hold_time); + dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev->fs_lcnt, + fs_mode ? &dev->sda_hold_time : NULL); + return 0; } |