Re: [PATCH] PCI: mvebu: Take control of mbus windows setup by the firmware

[Jason Gunthorpe]

Hey Thomas,

Could you take a look at this? Thanks

Jason

On Wed, Oct 26, 2016 at 11:44:40AM -0600, Jason Gunthorpe wrote:
> The firmware may setup the mbus to access PCI-E and indicate this
> has happened with a ranges mapping for the PCI-E ID. If this happens
> then the mbus setup and the pci dynamic setup conflict, creating
> problems.
> 
> Have PCI-E assume control of the firmware specified default mapping by
> setting the value of the bridge window to match the firmware mapping.
> 
> Signed-off-by: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
>  drivers/bus/mvebu-mbus.c     | 36 ++++++++++++++++++++++++++++++++++++
>  drivers/pci/host/pci-mvebu.c | 22 ++++++++++++++++++++++
>  include/linux/mbus.h         |  3 +++
>  3 files changed, 61 insertions(+)
> 
> In the DT this could look like:
> 
> 	mbus {
> 		ranges = <MBUS_ID(0x04, 0xe8) 0 0xe0000000 0x8000000 /* PEX 0 MEM */
> 		pex@e0000000 {
> 			compatible = "marvell,kirkwood-pcie";
> 			ranges = <0x82000000 0 0x40000 MBUS_ID(0xf0, 0x01) 0x40000 0 0x00002000 /* Controller regs */
> 				  0x82000000 1 0       MBUS_ID(0x04, 0xe8) 0 1 0 /* Port 0.0 MEM */
> 				  >;
> 			pcie@1,0 {
> 				ranges = <0x82000000 0 0 0x82000000 0x1 0 1 0>;
> 				reg = <0x0800 0 0  0 0>; // 0000:00:01.0
> 
> 				device@0 {
> 					reg = <0x0 0 0	0 0>; // 0000:01:00.0
> 					ranges = <0x00000000  0x82000000 0x00000000 0x00000000	0x8000000>;
> 
> Which is basically the OF way to describe PCI devices downstream of
> the interface and give information about what their BARs should be.
> 
> This is useful if there is even more DT stuff below the explicitly
> declared device as it allows standard DT address translation to work
> properly.
> 
> diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c
> index c7f396903184..ce0ac5049c1f 100644
> +++ b/drivers/bus/mvebu-mbus.c
> @@ -922,6 +922,42 @@ int mvebu_mbus_add_window_by_id(unsigned int target, unsigned int attribute,
>  						 size, MVEBU_MBUS_NO_REMAP);
>  }
>  
> +/**
> + * mvebu_mbus_get_single_window_by_id() - return the location of the window if
> + * the target/attribute has a single enabled mapping.
> + *
> + * RETURNS:
> + *	-ENODEV if no mapping and -E2BIG if there is more than one mapping
> + */
> +int mvebu_mbus_get_single_window_by_id(unsigned int target,
> +				       unsigned int attribute,
> +				       phys_addr_t *base, phys_addr_t *size)
> +{
> +	unsigned int win;
> +	unsigned int count = 0;
> +
> +	for (win = 0; win < mbus_state.soc->num_wins; win++) {
> +		u64 wbase;
> +		u32 wsize;
> +		u8 wtarget, wattr;
> +		int enabled;
> +
> +		mvebu_mbus_read_window(&mbus_state, win, &enabled, &wbase,
> +				       &wsize, &wtarget, &wattr, NULL);
> +		if (enabled && wtarget == target && wattr == attribute) {
> +			*base = wbase;
> +			*size = wsize;
> +			count++;
> +		}
> +	}
> +
> +	if (count == 1)
> +		return 0;
> +	if (count == 0)
> +		return -ENODEV;
> +	return -E2BIG;
> +}
> +
>  int mvebu_mbus_del_window(phys_addr_t base, size_t size)
>  {
>  	int win;
> diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
> index 307f81d6b479..5d5a2687b73e 100644
> +++ b/drivers/pci/host/pci-mvebu.c
> @@ -464,6 +464,8 @@ static void mvebu_pcie_handle_membase_change(struct mvebu_pcie_port *port)
>  static void mvebu_sw_pci_bridge_init(struct mvebu_pcie_port *port)
>  {
>  	struct mvebu_sw_pci_bridge *bridge = &port->bridge;
> +	int rc;
> +	phys_addr_t base, size;
>  
>  	memset(bridge, 0, sizeof(struct mvebu_sw_pci_bridge));
>  
> @@ -480,6 +482,26 @@ static void mvebu_sw_pci_bridge_init(struct mvebu_pcie_port *port)
>  
>  	/* Add capabilities */
>  	bridge->status = PCI_STATUS_CAP_LIST;
> +
> +	/*
> +	 * If the firmware has already setup a window for PCIe then assume
> +	 * control of it by defaulting the BAR to the window setting.
> +	 */
> +	rc = mvebu_mbus_get_single_window_by_id(port->mem_target,
> +						port->mem_attr, &base, &size);
> +	if (rc == -E2BIG)
> +		pr_err(FW_BUG "%s: Too many pre-existing mbus mappings\n",
> +		       port->dn->name);
> +	if (!rc) {
> +		if ((base & 0xFFFFF) != 0 || ((size + base) & 0xFFFFF) != 0)
> +			pr_err(FW_BUG "%s: Invalid pre-existing mbus mapping\n",
> +			       port->dn->name);
> +		port->memwin_base = base;
> +		port->memwin_size = size;
> +		port->bridge.membase = (base >> 16) & 0xFFF0;
> +		port->bridge.memlimit = ((size - 1 + base) >> 16) & 0xFFF0;
> +		port->bridge.command |= PCI_COMMAND_MEMORY;
> +	}
>  }
>  
>  /*
> diff --git a/include/linux/mbus.h b/include/linux/mbus.h
> index d610232762e3..dfafc27b41b5 100644
> +++ b/include/linux/mbus.h
> @@ -83,5 +83,8 @@ int mvebu_mbus_init(const char *soc, phys_addr_t mbus_phys_base,
>  		    size_t mbus_size, phys_addr_t sdram_phys_base,
>  		    size_t sdram_size);
>  int mvebu_mbus_dt_init(bool is_coherent);
> +int mvebu_mbus_get_single_window_by_id(unsigned int target,
> +				       unsigned int attribute,
> +				       phys_addr_t *base, phys_addr_t *size);
>  
>  #endif /* __LINUX_MBUS_H */