| Message ID | 20200221033640.55163-2-jaedon.shin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI: brcmstb: Add Broadcom STB support | expand |
On Fri, Feb 21, 2020 at 12:36:39PM +0900, Jaedon Shin wrote: > + supply-names: > + description: List of regulator supplies to use for PCIe > + No, this isn't a good idea - the set of supplies the device has is fixed when the silicon is produced, it's not something that needs to vary per board. This means that the binding should have a fixed list of supplies, per SoC if that's needed.
On 2/21/2020 4:12 AM, Mark Brown wrote: > On Fri, Feb 21, 2020 at 12:36:39PM +0900, Jaedon Shin wrote: > >> + supply-names: >> + description: List of regulator supplies to use for PCIe >> + > > No, this isn't a good idea - the set of supplies the device has is > fixed when the silicon is produced, it's not something that needs to > vary per board. This means that the binding should have a fixed list of > supplies, per SoC if that's needed. These are not the supplies for the PCIe I/Os on the SoCs side, but the supplies for the PCIe end-point connected to the SoCs. More on that below. What I suspect is going on is that Jaedon wants to use the canonical bootloader from Broadcom which provides the supplies in way that they are properties of the PCIe RC node as opposed to properties of the PCIe EP node. This has been done historically because there is a chicken and egg problem and we did not know or could solve this at the time. If you describe the regulators as properties of the PCIe EP nodes which are child nodes of the PCIe RC node (as we should), you will not be able to manage all of them within your pci_driver instance, because if there is no power to the EP you just do not enumerate it, therefore no pci_device is created. It seems to me that what we are missing is some logic within the PCI subsystem that is able to parse regulator/resets properties and ensure that they are enabled in order for a PCI bus scan to succeed. Jaedon, do you feel like taking on this effort? From these existing bindings: Documentation/devicetree/bindings/pci/nvidia,tegra20-pcie.txt Documentation/devicetree/bindings/pci/rockchip-pcie-host.txt Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt it seems to me that they are all describing the supplies from the SoC side, but not sure, there may have been a precedent for a similar simplification.
On Fri, Feb 21, 2020 at 08:33:36AM -0800, Florian Fainelli wrote: > On 2/21/2020 4:12 AM, Mark Brown wrote: > > No, this isn't a good idea - the set of supplies the device has is > > fixed when the silicon is produced, it's not something that needs to > > vary per board. This means that the binding should have a fixed list of > > supplies, per SoC if that's needed. > These are not the supplies for the PCIe I/Os on the SoCs side, but the > supplies for the PCIe end-point connected to the SoCs. More on that below. Then the "slots" (obviously at least some of these are soldered down rather than on actual slots) should be represented in DT and the controller or bus should know that it needs to iterate over them to bring up the chips. I would also expect that there are standard names in the PCI specs for the standard supplies that go into devices as part of the bus spec which would mean that there should still be no need to encode names like this. > If you describe the regulators as properties of the PCIe EP nodes which > are child nodes of the PCIe RC node (as we should), you will not be able > to manage all of them within your pci_driver instance, because if there > is no power to the EP you just do not enumerate it, therefore no > pci_device is created. The framework and/or driver can enumerate firmware information without actually powering up the devices of course. I would not be surprised to learn that most systems just mark the device supplies always on, it's not like the devices will be able to use them normally anyway.
On 2/21/20 9:11 AM, Mark Brown wrote: > On Fri, Feb 21, 2020 at 08:33:36AM -0800, Florian Fainelli wrote: >> On 2/21/2020 4:12 AM, Mark Brown wrote: > >>> No, this isn't a good idea - the set of supplies the device has is >>> fixed when the silicon is produced, it's not something that needs to >>> vary per board. This means that the binding should have a fixed list of >>> supplies, per SoC if that's needed. > >> These are not the supplies for the PCIe I/Os on the SoCs side, but the >> supplies for the PCIe end-point connected to the SoCs. More on that below. > > Then the "slots" (obviously at least some of these are soldered down > rather than on actual slots) should be represented in DT and the > controller or bus should know that it needs to iterate over them to > bring up the chips. I would also expect that there are standard names > in the PCI specs for the standard supplies that go into devices as part > of the bus spec which would mean that there should still be no need to > encode names like this. Agree. > >> If you describe the regulators as properties of the PCIe EP nodes which >> are child nodes of the PCIe RC node (as we should), you will not be able >> to manage all of them within your pci_driver instance, because if there >> is no power to the EP you just do not enumerate it, therefore no >> pci_device is created. > > The framework and/or driver can enumerate firmware information without > actually powering up the devices of course. The issue is not enumeration, it is ensuring that you will be able to establish the PCIe link with the EP. If there is no pci_device created because the bus scanning returned a link down, there is not much that can be done. Also the question is whether this logic belongs in the PCI bus layer or the driver. > > I would not be surprised to learn that most systems just mark the device > supplies always on, it's not like the devices will be able to use them > normally anyway. In the downstream PCIe driver which is this one is just a subset of until we close the gap, we have some additional logical to determine whether the EP device is wakeup enabled in order to leave its regulators turned on during system sleep so as to permit Wake-on-WLAN for instance.
On Fri, Feb 21, 2020 at 09:50:42AM -0800, Florian Fainelli wrote: > On 2/21/20 9:11 AM, Mark Brown wrote: > > The framework and/or driver can enumerate firmware information without > > actually powering up the devices of course. > The issue is not enumeration, it is ensuring that you will be able to > establish the PCIe link with the EP. If there is no pci_device created > because the bus scanning returned a link down, there is not much that > can be done. Also the question is whether this logic belongs in the PCI > bus layer or the driver. Given that the interface with the devices is all standardized I'd have expected it to be in the bus code as a first pass. > > I would not be surprised to learn that most systems just mark the device > > supplies always on, it's not like the devices will be able to use them > > normally anyway. > In the downstream PCIe driver which is this one is just a subset of > until we close the gap, we have some additional logical to determine > whether the EP device is wakeup enabled in order to leave its regulators > turned on during system sleep so as to permit Wake-on-WLAN for instance. Is that just using standard PCI stuff or is it custom for embedded applications?
diff --git a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml index 77d3e81a437b..efa5c885724b 100644 --- a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml +++ b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml @@ -56,6 +56,9 @@ properties: description: Indicates usage of spread-spectrum clocking. type: boolean + supply-names: + description: List of regulator supplies to use for PCIe + required: - reg - dma-ranges diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c index d20aabc26273..8968ef7fa55d 100644 --- a/drivers/pci/controller/pcie-brcmstb.c +++ b/drivers/pci/controller/pcie-brcmstb.c @@ -23,6 +23,7 @@ #include <linux/of_platform.h> #include <linux/pci.h> #include <linux/printk.h> +#include <linux/regulator/consumer.h> #include <linux/sizes.h> #include <linux/slab.h> #include <linux/string.h> @@ -173,6 +174,8 @@ struct brcm_pcie { int gen; u64 msi_target_addr; struct brcm_msi *msi; + struct regulator_bulk_data *vreg_bulk; + int num_vregs; }; /* @@ -898,6 +901,7 @@ static void __brcm_pcie_remove(struct brcm_pcie *pcie) { brcm_msi_remove(pcie); brcm_pcie_turn_off(pcie); + regulator_bulk_disable(pcie->num_vregs, pcie->vreg_bulk); clk_disable_unprepare(pcie->clk); clk_put(pcie->clk); } @@ -920,6 +924,8 @@ static int brcm_pcie_probe(struct platform_device *pdev) struct brcm_pcie *pcie; struct pci_bus *child; struct resource *res; + struct regulator_bulk_data *bulk; + int i; int ret; bridge = devm_pci_alloc_host_bridge(&pdev->dev, sizeof(*pcie)); @@ -955,6 +961,36 @@ static int brcm_pcie_probe(struct platform_device *pdev) return ret; } + ret = of_property_count_strings(np, "supply-names"); + pcie->num_vregs = (ret < 0) ? 0 : ret; + + if (pcie->num_vregs) { + bulk = devm_kcalloc(pcie->dev, pcie->num_vregs, sizeof(*bulk), + GFP_KERNEL); + if (!bulk) { + clk_disable_unprepare(pcie->clk); + return -ENOMEM; + } + + for (i = 0; i < pcie->num_vregs; i++) + of_property_read_string_index(np, "supply-names", i, + &bulk[i].supply); + + ret = devm_regulator_bulk_get(pcie->dev, pcie->num_vregs, bulk); + if (ret < 0) { + clk_disable_unprepare(pcie->clk); + return ret; + } + + pcie->vreg_bulk = bulk; + } + + ret = regulator_bulk_enable(pcie->num_vregs, pcie->vreg_bulk); + if (ret) { + clk_disable_unprepare(pcie->clk); + return ret; + } + ret = brcm_pcie_setup(pcie); if (ret) goto fail;
ARM-based Broadcom STB SoCs have GPIO-based voltage regulator for PCIe turning off/on power supplies. Signed-off-by: Jaedon Shin <jaedon.shin@gmail.com> --- .../bindings/pci/brcm,stb-pcie.yaml | 3 ++ drivers/pci/controller/pcie-brcmstb.c | 36 +++++++++++++++++++ 2 files changed, 39 insertions(+)