[PATCH] i2c: add support for microchip fpga i2c controllers

[Conor Dooley]

On 18/03/2022 14:56, Ben Dooks wrote:
> On 15/03/2022 15:32, Conor Dooley wrote:
>> Add Microchip CoreI2C i2c controller support. This driver supports the
>> "hard" i2c controller on the Microchip PolarFire SoC & the basic feature
>> set for "soft" i2c controller implemtations in the FPGA fabric.
>>
>> Co-developed-by: Daire McNamara <daire.mcnamara at microchip.com>
>> Signed-off-by: Daire McNamara <daire.mcnamara at microchip.com>
>> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
>> ---
>>   drivers/i2c/busses/Kconfig              |  11 +
>>   drivers/i2c/busses/Makefile             |   1 +
>>   drivers/i2c/busses/i2c-microchip-core.c | 487 ++++++++++++++++++++++++
>>   3 files changed, 499 insertions(+)
>>   create mode 100644 drivers/i2c/busses/i2c-microchip-core.c
>>
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index a1bae59208e3..3d4d8e0e9de7 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -781,6 +781,17 @@ config I2C_MESON
>>         If you say yes to this option, support will be included for the
>>         I2C interface on the Amlogic Meson family of SoCs.
> 
> snip
> 
>> +
>> +static void mchp_corei2c_core_disable(struct mchp_corei2c_dev *idev)
>> +{
>> +    u8 ctrl = readl(idev->base + CORE_I2C_CTRL);
>> +
>> +    ctrl &= ~CTRL_ENS1;
>> +    writel(ctrl, idev->base + CORE_I2C_CTRL);
>> +}
>> +
>> +static void mchp_corei2c_core_enable(struct mchp_corei2c_dev *idev)
>> +{
>> +    u8 ctrl = readl(idev->base + CORE_I2C_CTRL);
>> +
>> +    ctrl |= CTRL_ENS1;
>> +    writel(ctrl, idev->base + CORE_I2C_CTRL);
>> +}
> 
> Not sure why you would use readl/writel with an u8, surely an
> readb/writeb be better?

Sure, can try drop it to b.

> 
> 
>> +static irqreturn_t mchp_corei2c_handle_isr(struct mchp_corei2c_dev 
>> *idev)
>> +{
>> +    u32 status = idev->isr_status;
>> +    u8 ctrl;
>> +
>> +    if (!idev->buf) {
>> +        dev_warn(idev->dev, "unexpected interrupt\n");
>> +        return IRQ_HANDLED;
>> +    }
> 
> is IRQ_HANDLED correct here?

Hmm, the dev_warn is probably incorrect too. For the mpfs, the interrupt 
line isn't shared, but the generic fabric core could be. Ill change this.

> 
>> +
>> +static int mchp_corei2c_probe(struct platform_device *pdev)
>> +{
>> +    struct mchp_corei2c_dev *idev = NULL;
>> +    struct resource *res;
>> +    int irq, ret;
>> +    u32 val;
>> +
>> +    idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
>> +    if (!idev)
>> +        return -ENOMEM;
>> +
>> +    idev->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
>> +    if (IS_ERR(idev->base))
>> +        return PTR_ERR(idev->base);
>> +
>> +    irq = platform_get_irq(pdev, 0);
>> +    if (irq < 0)
>> +        return dev_err_probe(&pdev->dev, irq,
>> +                     "missing interrupt resource\n");
>> +
>> +    idev->i2c_clk = devm_clk_get(&pdev->dev, NULL);
>> +    if (IS_ERR(idev->i2c_clk))
>> +        return dev_err_probe(&pdev->dev, PTR_ERR(idev->i2c_clk),
>> +                     "missing clock\n");
>> +
>> +    idev->dev = &pdev->dev;
>> +    init_completion(&idev->msg_complete);
>> +    spin_lock_init(&idev->lock);
>> +
>> +    val = device_property_read_u32(idev->dev, "clock-frequency",
>> +                       &idev->bus_clk_rate);
>> +    if (val) {
>> +        dev_info(&pdev->dev, "default to 100kHz\n");
>> +        idev->bus_clk_rate = 100000;
>> +    }
>> +
>> +    if (idev->bus_clk_rate > 400000)
>> +        return dev_err_probe(&pdev->dev, -EINVAL,
>> +                     "clock-frequency too high: %d\n",
>> +                     idev->bus_clk_rate);
>> +
>> +    ret = devm_request_irq(&pdev->dev, irq, mchp_corei2c_isr, 
>> IRQF_SHARED,
>> +                   pdev->name, idev);
>> +    if (ret)
>> +        return dev_err_probe(&pdev->dev, ret,
>> +                     "failed to claim irq %d\n", irq);
>> +
>> +    ret = clk_prepare_enable(idev->i2c_clk);
>> +    if (ret)
>> +        return dev_err_probe(&pdev->dev, ret,
>> +                     "failed to enable clock\n");
>> +
>> +    ret = mchp_corei2c_init(idev);
>> +    if (ret)
>> +        return dev_err_probe(&pdev->dev, ret,
>> +                     "failed to program clock divider\n");
> 
> going to leak a prepared clock from here on?

Aye, good spot. Thanks.

>> +    i2c_set_adapdata(&idev->adapter, idev);
>> +    snprintf(idev->adapter.name, sizeof(idev->adapter.name),
>> +         "Microchip I2C hw bus");
>> +    idev->adapter.owner = THIS_MODULE;
>> +    idev->adapter.algo = &mchp_corei2c_algo;
>> +    idev->adapter.dev.parent = &pdev->dev;
>> +    idev->adapter.dev.of_node = pdev->dev.of_node;
>> +
>> +    platform_set_drvdata(pdev, idev);
>> +
>> +    ret = i2c_add_adapter(&idev->adapter);
>> +    if (ret) {
>> +        clk_disable_unprepare(idev->i2c_clk);
>> +        return ret;
>> +    }
>> +
>> +    dev_info(&pdev->dev, "Microchip I2C Probe Complete\n");
> 
> not sure if necessary, doesn't the i2c core also announce?

The only thing I see on boot is this, but I'll take a look and see if I 
can do this via the core.

> 
>> +    return 0;
>> +}
>> +
>> +static int mchp_corei2c_remove(struct platform_device *pdev)
>> +{
>> +    struct mchp_corei2c_dev *idev = platform_get_drvdata(pdev);
>> +
>> +    clk_disable_unprepare(idev->i2c_clk);
>> +    i2c_del_adapter(&idev->adapter);
>> +
>> +    return 0;
>> +}
>> +
>> +static const struct of_device_id mchp_corei2c_of_match[] = {
>> +    { .compatible = "microchip,mpfs-i2c" },
>> +    { .compatible = "microchip,corei2c-rtl-v7" },
>> +    {},
>> +};
>> +MODULE_DEVICE_TABLE(of, mchp_corei2c_of_match);
>> +
>> +static struct platform_driver mchp_corei2c_driver = {
>> +    .probe = mchp_corei2c_probe,
>> +    .remove = mchp_corei2c_remove,
>> +    .driver = {
>> +        .name = "microchip-corei2c",
>> +        .of_match_table = mchp_corei2c_of_match,
>> +    },
>> +};
>> +
>> +module_platform_driver(mchp_corei2c_driver);
>> +
>> +MODULE_DESCRIPTION("Microchip CoreI2C bus driver");
>> +MODULE_AUTHOR("Daire McNamara <daire.mcnamara at microchip.com>");
>> +MODULE_AUTHOR("Conor Dooley <conor.dooley at microchip.com>");
>> +MODULE_LICENSE("GPL v2");
> 
>