[PATCH 26/42] PCI: aardvark: Fix support for bus mastering and PCI_COMMAND on emulated bridge
From: Pali Rohár <pali@kernel.org>
Date: 2021-05-06 15:36:22
Also in:
linux-pci, lkml
Subsystem:
pci driver for aardvark (marvell armada 3700), pci native host bridge and endpoint drivers, pci subsystem, the rest · Maintainers:
Thomas Petazzoni, Pali Rohár, Lorenzo Pieralisi, Krzysztof Wilczyński, Manivannan Sadhasivam, Bjorn Helgaas, Linus Torvalds
From very vague, ambiguous and incomplete information from Marvell we
deduced that the 32-bit aardvark register 0x4 (PCIE_CORE_CMD_STATUS_REG),
which is not documented in Armada 3700 Functional Specifications for PCIe
Root Complex mode, should control two 16-bit PCIe registers: Command
Register and Status Registers of virtual PCIe Root Bridge.
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 beginning of aardvark
initialization.
Also 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.
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Fixes: 8a3ebd8de328 ("PCI: aardvark: Implement emulated root PCI bridge config space")
Cc: stable@vger.kernel.org # b2a56469d550 ("PCI: aardvark: Add FIXME comment for PCIE_CORE_CMD_STATUS_REG access")
---
drivers/pci/controller/pci-aardvark.c | 54 +++++++++++++++++++--------
1 file changed, 38 insertions(+), 16 deletions(-)
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 6c860e67e5a2..92f93ec48d6b 100644
--- 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
@@ -365,6 +362,11 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) 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 |
@@ -443,19 +445,6 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) advk_writel(pcie, reg, PIO_CTRL); 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, u32 *val)
@@ -555,6 +544,37 @@ static int advk_pcie_wait_pio(struct advk_pcie *pcie) 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,
@@ -624,6 +644,8 @@ advk_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge, } 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, };
--
2.20.1
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