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PCI: aardvark: Fix support for bus mastering and PCI_COMMAND on emulated bridge

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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: 8a3ebd8de3 ("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 # b2a56469d5 ("PCI: aardvark: Add FIXME comment for PCIE_CORE_CMD_STATUS_REG access")
This commit is contained in:
Pali Rohár 2021-10-28 20:56:56 +02:00 committed by Lorenzo Pieralisi
parent 95997723b6
commit 771153fc88
1 changed files with 38 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

54
drivers/pci/controller/pci-aardvark.c
View file

@ -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
@ -514,6 +511,11 @@ 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 |
@ -612,19 +614,6 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
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)
@ -753,6 +742,37 @@ 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,
@ -854,6 +874,8 @@ 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,
};