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SubjectRe: [PATCH 3/3] PCI: apple: Add support for optional PWREN GPIO
On Mon, 02 May 2022 10:38:32 +0100,
Hector Martin <marcan@marcan.st> wrote:
>
> WiFi and SD card devices on M1 Macs have a separate power enable GPIO.
> Add support for this to the PCIe controller. This is modeled after how
> pcie-fu740 does it.

Please update the DT binding to reflect this as an optional property.

>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---
> drivers/pci/controller/pcie-apple.c | 35 ++++++++++++++++++++++++++---
> 1 file changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index e3aa2d461739..5b73c03ebe94 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -518,6 +518,16 @@ static int apple_pcie_probe_port(struct device_node *np)
> }
>
> gpiod_put(gd);
> +
> + gd = gpiod_get_from_of_node(np, "pwren-gpios", 0,
> + GPIOD_OUT_LOW, "PWREN");
> + if (IS_ERR(gd)) {
> + if (PTR_ERR(gd) != -ENOENT)
> + return PTR_ERR(gd);
> + } else {
> + gpiod_put(gd);
> + }
> +
> return 0;
> }
>
> @@ -526,7 +536,7 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
> {
> struct platform_device *platform = to_platform_device(pcie->dev);
> struct apple_pcie_port *port;
> - struct gpio_desc *reset;
> + struct gpio_desc *reset, *pwren = NULL;
> u32 stat, idx;
> int ret, i;
>
> @@ -535,6 +545,15 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
> if (IS_ERR(reset))
> return PTR_ERR(reset);
>
> + pwren = devm_gpiod_get_from_of_node(pcie->dev, np, "pwren-gpios", 0,
> + GPIOD_OUT_LOW, "PWREN");
> + if (IS_ERR(pwren)) {
> + if (PTR_ERR(pwren) == -ENOENT)
> + pwren = NULL;
> + else
> + return PTR_ERR(pwren);
> + }
> +
> port = devm_kzalloc(pcie->dev, sizeof(*port), GFP_KERNEL);
> if (!port)
> return -ENOMEM;
> @@ -557,12 +576,22 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
> /* Assert PERST# before setting up the clock */
> gpiod_set_value_cansleep(reset, 1);
>
> + /* Power on the device if required */
> + if (pwren)
> + gpiod_set_value_cansleep(pwren, 1);

nit: AFAICT, the gpiod_* helpers already check for a NULL descriptor,
and silently return without an error.

> +
> ret = apple_pcie_setup_refclk(pcie, port);
> if (ret < 0)
> return ret;
>
> - /* The minimal Tperst-clk value is 100us (PCIe CEM r5.0, 2.9.2) */
> - usleep_range(100, 200);
> + /*
> + * The minimal Tperst-clk value is 100us (PCIe CEM r5.0, 2.9.2)
> + * If powering up, the minimal Tpvperl is 100ms
> + */
> + if (pwren)
> + msleep(100);
> + else
> + usleep_range(100, 200);
>
> /* Deassert PERST# */
> rmw_set(PORT_PERST_OFF, port->base + PORT_PERST);

With the documentation aspect addressed:

Acked-by: Marc Zyngier <maz@kernel.org>

M.

--
Without deviation from the norm, progress is not possible.

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