On Sun, May 25, 2025 at 06:04:03PM +0200, Marek Vasut wrote:
> Add the ability to enable optional slot clock into the pwrctrl driver.
> This is used to enable slot clock in split-clock topologies, where the
> PCIe host/controller supply and PCIe slot supply are not provided by
> the same clock. The PCIe host/controller clock should be described in
> the controller node as the controller clock, while the slot clock should
> be described in controller bridge/slot subnode.
>
> Example DT snippet:
> &pcicontroller {
> clocks = <&clk_dif 0>; /* PCIe controller clock */
>
> pci@0,0 {
> #address-cells = <3>;
> #size-cells = <2>;
> reg = <0x0 0x0 0x0 0x0 0x0>;
> compatible = "pciclass,0604";
> device_type = "pci";
> clocks = <&clk_dif 1>; /* PCIe slot clock */
> vpcie3v3-supply = <®_3p3v>;
> ranges;
> };
> };
>
> Example clock topology:
> ____________ ____________
> | PCIe host | | PCIe slot |
> | | | |
> | PCIe RX<|==================|>PCIe TX |
> | PCIe TX<|==================|>PCIe RX |
> | | | |
> | PCIe CLK<|======.. ..======|>PCIe CLK |
> '------------' || || '------------'
> || ||
> ____________ || ||
> | 9FGV0441 | || ||
> | | || ||
> | CLK DIF0<|======'' ||
> | CLK DIF1<|==========''
> | CLK DIF2<|
> | CLK DIF3<|
> '------------'
>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
- Mani
> ---
> Cc: Bartosz Golaszewski <brgl@xxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Conor Dooley <conor+dt@xxxxxxxxxx>
> Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzk+dt@xxxxxxxxxx>
> Cc: Magnus Damm <magnus.damm@xxxxxxxxx>
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-pci@xxxxxxxxxxxxxxx
> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
> ---
> drivers/pci/pwrctrl/slot.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/pci/pwrctrl/slot.c b/drivers/pci/pwrctrl/slot.c
> index 18becc144913e..222c14056cfae 100644
> --- a/drivers/pci/pwrctrl/slot.c
> +++ b/drivers/pci/pwrctrl/slot.c
> @@ -4,6 +4,7 @@
> * Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> */
>
> +#include <linux/clk.h>
> #include <linux/device.h>
> #include <linux/mod_devicetable.h>
> #include <linux/module.h>
> @@ -30,6 +31,7 @@ static int pci_pwrctrl_slot_probe(struct platform_device *pdev)
> {
> struct pci_pwrctrl_slot_data *slot;
> struct device *dev = &pdev->dev;
> + struct clk *clk;
> int ret;
>
> slot = devm_kzalloc(dev, sizeof(*slot), GFP_KERNEL);
> @@ -50,6 +52,13 @@ static int pci_pwrctrl_slot_probe(struct platform_device *pdev)
> goto err_regulator_free;
> }
>
> + clk = devm_clk_get_optional_enabled(dev, NULL);
> + if (IS_ERR(clk)) {
> + ret = PTR_ERR(clk);
> + dev_err_probe(dev, ret, "Failed to enable slot clock\n");
> + goto err_regulator_disable;
> + }
> +
> ret = devm_add_action_or_reset(dev, devm_pci_pwrctrl_slot_power_off,
> slot);
> if (ret)
> --
> 2.47.2
>
--
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