This patch implements PCI hotplug support for iproc family chipsets. iproc based SOC (e.g. Stingray) does not have hotplug controller integrated. Hence, standard PCI hotplug framework hooks can-not be used. e.g. controlled power up/down of slot.
The mechanism, for e.g. Stingray has adopted for PCI hotplug is as follows: PCI present lines are input to GPIOs depending on the type of connector (x2, x4, x8). The implementation essentially takes care of following: > Initializing hotplug irq thread. > Detecting the endpoint device based on link state. > Handling PERST and detecting the plugged devices. > Ordered Hot plug-out, where User is expected to write 1 to /sys/bus/pci/devices/<pci_dev>/remove > Handling spurious interrupt > Handling multiple interrupts and makes sure that card is enumerated only once. Signed-off-by: Oza Pawandeep <[email protected]> Reviewed-by: Ray Jui <[email protected]> diff --git a/drivers/pci/host/pcie-iproc-platform.c b/drivers/pci/host/pcie-iproc-platform.c index 9512960..e1eb141 100644 --- a/drivers/pci/host/pcie-iproc-platform.c +++ b/drivers/pci/host/pcie-iproc-platform.c @@ -89,6 +89,9 @@ static int iproc_pcie_pltfm_probe(struct platform_device *pdev) pcie->need_ob_cfg = true; } + if (of_property_read_bool(np, "slot-pluggable")) + pcie->enable_hotplug = true; + /* PHY use is optional */ pcie->phy = devm_phy_get(dev, "pcie-phy"); if (IS_ERR(pcie->phy)) { diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c index ee40651..eb919f7 100644 --- a/drivers/pci/host/pcie-iproc.c +++ b/drivers/pci/host/pcie-iproc.c @@ -28,6 +28,7 @@ #include <linux/of_irq.h> #include <linux/of_platform.h> #include <linux/phy/phy.h> +#include <linux/gpio.h> #include "pcie-iproc.h" @@ -65,6 +66,17 @@ #define PCIE_DL_ACTIVE_SHIFT 2 #define PCIE_DL_ACTIVE BIT(PCIE_DL_ACTIVE_SHIFT) +#define CFG_RC_LTSSM 0x1cf8 +#define CFG_RC_PHY_CTL 0x1804 +#define CFG_RC_LTSSM_TIMEOUT 1000 +#define CFG_RC_LTSSM_STATE_MASK 0xff +#define CFG_RC_LTSSM_STATE_L1 0x1 + +#define CFG_RC_CLR_LTSSM_HIST_SHIFT 29 +#define CFG_RC_CLR_LTSSM_HIST_MASK BIT(CFG_RC_CLR_LTSSM_HIST_SHIFT) +#define CFG_RC_CLR_RECOV_HIST_SHIFT 31 +#define CFG_RC_CLR_RECOV_HIST_MASK BIT(CFG_RC_CLR_RECOV_HIST_SHIFT) + #define APB_ERR_EN_SHIFT 0 #define APB_ERR_EN BIT(APB_ERR_EN_SHIFT) @@ -1306,12 +1318,106 @@ static int iproc_pcie_rev_init(struct iproc_pcie *pcie) return 0; } +static bool iproc_pci_hp_check_ltssm(struct iproc_pcie *pcie) +{ + struct pci_bus *bus = pcie->root_bus; + u32 val, timeout = CFG_RC_LTSSM_TIMEOUT; + + /* Clear LTSSM history. */ + pci_bus_read_config_dword(pcie->root_bus, 0, + CFG_RC_PHY_CTL, &val); + pci_bus_write_config_dword(bus, 0, CFG_RC_PHY_CTL, + val | CFG_RC_CLR_RECOV_HIST_MASK | + CFG_RC_CLR_LTSSM_HIST_MASK); + /* write back the origional value. */ + pci_bus_write_config_dword(bus, 0, CFG_RC_PHY_CTL, val); + + do { + pci_bus_read_config_dword(pcie->root_bus, 0, + CFG_RC_LTSSM, &val); + /* check link state to see if link moved to L1 state. */ + if ((val & CFG_RC_LTSSM_STATE_MASK) == + CFG_RC_LTSSM_STATE_L1) + return true; + timeout--; + usleep_range(500, 1000); + } while (timeout); + + return false; +} + +static irqreturn_t iproc_pci_hotplug_thread(int irq, void *data) +{ + struct iproc_pcie *pcie = data; + struct pci_bus *bus = pcie->root_bus, *child; + bool link_status; + + iproc_pcie_perst_ctrl(pcie, true); + iproc_pcie_perst_ctrl(pcie, false); + + link_status = iproc_pci_hp_check_ltssm(pcie); + + if (link_status && + !iproc_pcie_check_link(pcie, bus) && + !pcie->ep_is_present) { + pci_rescan_bus(bus); + list_for_each_entry(child, &bus->children, node) + pcie_bus_configure_settings(child); + pcie->ep_is_present = true; + dev_info(pcie->dev, + "PCI Hotplug: <device detected and enumerated>\n"); + } else if (link_status && pcie->ep_is_present) + /* + * ep_is_present makes sure, enumuration done only once. + * So it can handle spurious intrrupts, and also if we + * get multiple interrupts for all the implemented pins, + * we handle it only once. + */ + dev_info(pcie->dev, + "PCI Hotplug: <device already present>\n"); + else { + iproc_pcie_perst_ctrl(pcie, true); + pcie->ep_is_present = false; + dev_info(pcie->dev, + "PCI Hotplug: <device removed>\n"); + } + return IRQ_HANDLED; +} + +static int iproc_pci_hp_gpio_irq_get(struct iproc_pcie *pcie) +{ + struct gpio_descs *hp_gpiod; + struct device *dev = pcie->dev; + int i; + + hp_gpiod = devm_gpiod_get_array(dev, "prsnt", GPIOD_IN); + if (PTR_ERR(hp_gpiod) == -EPROBE_DEFER) + return -EPROBE_DEFER; + + if (!IS_ERR(hp_gpiod) && (hp_gpiod->ndescs > 0)) { + for (i = 0; i < hp_gpiod->ndescs; ++i) { + gpiod_direction_input(hp_gpiod->desc[i]); + if (request_threaded_irq(gpiod_to_irq + (hp_gpiod->desc[i]), + NULL, iproc_pci_hotplug_thread, + IRQF_TRIGGER_FALLING, + "PCI-hotplug", pcie)) + dev_err(dev, + "PCI hotplug prsnt: request irq failed\n"); + } + } + pcie->ep_is_present = false; + + return 0; +} + int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res) { struct device *dev; int ret; void *sysdata; struct pci_bus *bus, *child; + bool is_link_active; dev = pcie->dev; @@ -1337,6 +1443,12 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res) goto err_exit_phy; } + if (pcie->enable_hotplug) { + ret = iproc_pci_hp_gpio_irq_get(pcie); + if (ret < 0) + return ret; + } + iproc_pcie_perst_ctrl(pcie, true); iproc_pcie_perst_ctrl(pcie, false); @@ -1367,8 +1479,11 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res) } pcie->root_bus = bus; - ret = iproc_pcie_check_link(pcie, bus); - if (ret) { + is_link_active = iproc_pcie_check_link(pcie, bus); + if (is_link_active && pcie->enable_hotplug) { + dev_err(dev, "no PCIe EP device detected\n"); + iproc_pcie_perst_ctrl(pcie, true); + } else if (is_link_active) { dev_err(dev, "no PCIe EP device detected\n"); goto err_rm_root_bus; } @@ -1379,14 +1494,17 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res) if (iproc_pcie_msi_enable(pcie)) dev_info(dev, "not using iProc MSI\n"); - pci_scan_child_bus(bus); - pci_assign_unassigned_bus_resources(bus); + if (!is_link_active) { + pci_scan_child_bus(bus); + pci_assign_unassigned_bus_resources(bus); + } if (pcie->map_irq) pci_fixup_irqs(pci_common_swizzle, pcie->map_irq); - list_for_each_entry(child, &bus->children, node) - pcie_bus_configure_settings(child); + if (!is_link_active) + list_for_each_entry(child, &bus->children, node) + pcie_bus_configure_settings(child); pci_bus_add_devices(bus); diff --git a/drivers/pci/host/pcie-iproc.h b/drivers/pci/host/pcie-iproc.h index a6b55ce..e5d0cd4 100644 --- a/drivers/pci/host/pcie-iproc.h +++ b/drivers/pci/host/pcie-iproc.h @@ -77,6 +77,10 @@ struct iproc_pcie_ib { * @ib: inbound mapping related parameters * @ib_map: outbound mapping region related parameters * + * @enable_hotplug: indicates PCI hotplug feature is enabled + * @ep_is_present: when PCIe hotplug is enabled, this flag is used to + * indicate whether or not the endpoint device is present + * * @need_msi_steer: indicates additional configuration of the iProc PCIe * controller is required to steer MSI writes to external interrupt controller * @msi: MSI data @@ -104,6 +108,9 @@ struct iproc_pcie { struct iproc_pcie_ib ib; const struct iproc_pcie_ib_map *ib_map; + bool enable_hotplug; + bool ep_is_present; + bool need_msi_steer; struct iproc_msi *msi; }; -- 1.9.1
