From: Pali Rohár pali@kernel.org
commit 771153fc884f566a89af2d30033b7f3bc6e24e84 upstream.
From very vague, ambiguous and incomplete information from Marvell we
deduced that the 32-bit Aardvark register at address 0x4 (PCIE_CORE_CMD_STATUS_REG), which is not documented for Root Complex mode in the Functional Specification (only for Endpoint mode), controls two 16-bit PCIe registers: Command Register and Status Registers of PCIe Root Port.
This means that bit 2 controls bus mastering and forwarding of memory and I/O requests in the upstream direction. According to PCI specifications bits [0:2] of Command Register, this should be by default disabled on reset. So explicitly disable these bits at early setup of the Aardvark driver.
Remove code which unconditionally enables all 3 bits and let kernel code (via pci_set_master() function) to handle bus mastering of Root PCIe Bridge via emulated PCI_COMMAND on emulated bridge.
Link: https://lore.kernel.org/r/20211028185659.20329-5-kabel@kernel.org Fixes: 8a3ebd8de328 ("PCI: aardvark: Implement emulated root PCI bridge config space") Signed-off-by: Pali Rohár pali@kernel.org Signed-off-by: Marek Behún kabel@kernel.org Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Cc: stable@vger.kernel.org # b2a56469d550 ("PCI: aardvark: Add FIXME comment for PCIE_CORE_CMD_STATUS_REG access") Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/controller/pci-aardvark.c | 54 +++++++++++++++++++++++----------- 1 file changed, 38 insertions(+), 16 deletions(-)
--- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -31,9 +31,6 @@ /* PCIe core registers */ #define PCIE_CORE_DEV_ID_REG 0x0 #define PCIE_CORE_CMD_STATUS_REG 0x4 -#define PCIE_CORE_CMD_IO_ACCESS_EN BIT(0) -#define PCIE_CORE_CMD_MEM_ACCESS_EN BIT(1) -#define PCIE_CORE_CMD_MEM_IO_REQ_EN BIT(2) #define PCIE_CORE_DEV_REV_REG 0x8 #define PCIE_CORE_PCIEXP_CAP 0xc0 #define PCIE_CORE_ERR_CAPCTL_REG 0x118 @@ -563,6 +560,11 @@ static void advk_pcie_setup_hw(struct ad reg = (PCI_VENDOR_ID_MARVELL << 16) | PCI_VENDOR_ID_MARVELL; advk_writel(pcie, reg, VENDOR_ID_REG);
+ /* Disable Root Bridge I/O space, memory space and bus mastering */ + reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); + reg &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER); + advk_writel(pcie, reg, PCIE_CORE_CMD_STATUS_REG); + /* Set Advanced Error Capabilities and Control PF0 register */ reg = PCIE_CORE_ERR_CAPCTL_ECRC_CHK_TX | PCIE_CORE_ERR_CAPCTL_ECRC_CHK_TX_EN | @@ -660,19 +662,6 @@ static void advk_pcie_setup_hw(struct ad advk_pcie_disable_ob_win(pcie, i);
advk_pcie_train_link(pcie); - - /* - * FIXME: The following register update is suspicious. This register is - * applicable only when the PCI controller is configured for Endpoint - * mode, not as a Root Complex. But apparently when this code is - * removed, some cards stop working. This should be investigated and - * a comment explaining this should be put here. - */ - reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); - reg |= PCIE_CORE_CMD_MEM_ACCESS_EN | - PCIE_CORE_CMD_IO_ACCESS_EN | - PCIE_CORE_CMD_MEM_IO_REQ_EN; - advk_writel(pcie, reg, PCIE_CORE_CMD_STATUS_REG); }
static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u32 *val) @@ -793,6 +782,37 @@ static int advk_pcie_wait_pio(struct adv return -ETIMEDOUT; }
+static pci_bridge_emul_read_status_t +advk_pci_bridge_emul_base_conf_read(struct pci_bridge_emul *bridge, + int reg, u32 *value) +{ + struct advk_pcie *pcie = bridge->data; + + switch (reg) { + case PCI_COMMAND: + *value = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); + return PCI_BRIDGE_EMUL_HANDLED; + + default: + return PCI_BRIDGE_EMUL_NOT_HANDLED; + } +} + +static void +advk_pci_bridge_emul_base_conf_write(struct pci_bridge_emul *bridge, + int reg, u32 old, u32 new, u32 mask) +{ + struct advk_pcie *pcie = bridge->data; + + switch (reg) { + case PCI_COMMAND: + advk_writel(pcie, new, PCIE_CORE_CMD_STATUS_REG); + break; + + default: + break; + } +}
static pci_bridge_emul_read_status_t advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge, @@ -893,6 +913,8 @@ advk_pci_bridge_emul_pcie_conf_write(str }
static struct pci_bridge_emul_ops advk_pci_bridge_emul_ops = { + .read_base = advk_pci_bridge_emul_base_conf_read, + .write_base = advk_pci_bridge_emul_base_conf_write, .read_pcie = advk_pci_bridge_emul_pcie_conf_read, .write_pcie = advk_pci_bridge_emul_pcie_conf_write, };