On Tue, Jul 10 2018, Sergio Paracuellos wrote:
> map_bus callback is called before every .read/.write operation.
> Implement it and change custom read write operations for the
> pci subsystem generics. Make the probe function to assign data
> for controller data and get pci register base from device tree.
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@xxxxxxxxx>
> ---
> drivers/staging/mt7621-pci/pci-mt7621.c | 76 +++++++++++++++++++++++++++++++--
> 1 file changed, 72 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/mt7621-pci/pci-mt7621.c b/drivers/staging/mt7621-pci/pci-mt7621.c
> index 58c77bd..7bd06a0 100644
> --- a/drivers/staging/mt7621-pci/pci-mt7621.c
> +++ b/drivers/staging/mt7621-pci/pci-mt7621.c
> @@ -52,6 +52,9 @@
> #include <linux/delay.h>
> #include <linux/of.h>
> #include <linux/of_pci.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> #include <linux/platform_device.h>
>
> #include <ralink_regs.h>
> @@ -306,15 +309,31 @@ pci_config_write(struct pci_bus *bus, unsigned int devfn, int where, int size, u
> }
> }
>
> +static void __iomem *mt7621_pcie_map_bus(struct pci_bus *bus,
> + unsigned int devfn, int where)
> +{
> + struct mt7621_pcie_port *port = bus->sysdata;
> + u32 address = mt7621_pci_get_cfgaddr(bus->number, PCI_SLOT(devfn),
> + PCI_FUNC(devfn), where);
> + u32 address_reg, data_reg;
> +
> + address_reg = RALINK_PCI_CONFIG_ADDR;
> + data_reg = RALINK_PCI_CONFIG_DATA_VIRTUAL_REG;
> +
> + writel(address, port->reg_base + address_reg);
> +
> + return port->reg_base + data_reg;
> +}
> +
> struct pci_ops mt7621_pci_ops = {
> - .read = pci_config_read,
> - .write = pci_config_write,
> + .map_bus = mt7621_pcie_map_bus,
> + .read = pci_generic_config_read32,
> + .write = pci_generic_config_write32,
> };
>
> static struct resource mt7621_res_pci_mem1;
> static struct resource mt7621_res_pci_io1;
> static struct pci_controller mt7621_controller = {
> - .pci_ops = &mt7621_pci_ops,
> .mem_resource = &mt7621_res_pci_mem1,
> .io_resource = &mt7621_res_pci_io1,
> };
> @@ -489,10 +508,60 @@ void setup_cm_memory_region(struct resource *mem_resource)
> }
> }
>
> +static int mt7621_pcie_parse_dt(struct mt7621_pcie_port *port)
> +{
> + struct device *dev = port->dev;
> + struct device_node *node = dev->of_node;
> + struct resource regs;
> + const char *type;
> + int err;
> +
> + type = of_get_property(node, "device_type", NULL);
> + if (!type || strcmp(type, "pci")) {
> + dev_err(dev, "invalid \"device_type\" %s\n", type);
> + return -EINVAL;
> + }
> +
> + err = of_address_to_resource(node, 0, ®s);
> + if (err) {
> + dev_err(dev, "missing \"reg\" property\n");
> + return err;
> + }
> +
> + port->reg_base = devm_pci_remap_cfg_resource(dev, ®s);
> + if (IS_ERR(port->reg_base))
> + return PTR_ERR(port->reg_base);
> +
> + return 0;
> +}
> +
> static int mt7621_pci_probe(struct platform_device *pdev)
> {
> + struct device *dev = &pdev->dev;
> + struct mt7621_pcie_port *port;
> + struct pci_host_bridge *bridge;
> + int err;
> unsigned long val = 0;
>
> + bridge = devm_pci_alloc_host_bridge(dev, sizeof(*port));
> + if (!bridge)
> + return -ENODEV;
> +
> + port = pci_host_bridge_priv(bridge);
> + port->dev = dev;
> +
> + err = mt7621_pcie_parse_dt(port);
> + if (err) {
> + dev_err(dev, "Parsing DT failed\n");
> + return err;
> + }
> +
> + bridge->dev.parent = dev;
> + bridge->sysdata = port;
> + bridge->ops = &mt7621_pci_ops;
> + mt7621_controller.bus = bridge->bus;
bridge->bus hasn't been initialized yet, so it is NULL.
> + mt7621_controller.bus->ops = bridge->ops;
So this is a NULL-pointer deref.
Maybe you need to call pci_host_probe() somewhere? or
pci_scan_root_bus_bridge()?
Inserting either of those calls just after setting bridge->ops above
results in a hang, so something more subtle must been needed.
Thanks,
NeilBrown
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