[PATCH] Add support for turning PCIe ECRC on or off

From: Andrew Patterson
Date: Thu Apr 02 2009 - 18:18:07 EST

Add support for turning PCIe ECRC on or off

Adds support for PCI Express transaction layer end-to-end CRC checking
(ECRC). This patch will enable/disable ECRC checking by setting/clearing
the ECRC Check Enable and/or ECRC Generation Enable bits for devices that
support ECRC.

The ECRC setting is controlled by the "pcie_ecrc=" command-line option. If
this option is not set or is set to 'default", the enable and generation
bits are left in whatever state that firmware/BIOS sets them to. The
"off" setting turns them off, and the "on" option turns them on (if the
device supports it).

Signed-off-by: Andrew Patterson <andrew.patterson@xxxxxx>
---

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1754fed..c346b55 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1776,6 +1776,12 @@ and is between 256 and 4096 characters. It is defined in the file
force Enable ASPM even on devices that claim not to support it.
WARNING: Forcing ASPM on may cause system lockups.

+ pcie_ecrc= [PCI] Enable/disable PCIe ECRC (transaction layer
+ end-to-end CRC checking).
+ pcie_ecrc=default: Use BIOS/firmware settings.
+ pcie_ecrc=off: Turn ECRC off
+ pcie_ecrc=on: Turn ECRC on.
+
pcmv= [HW,PCMCIA] BadgePAD 4

pd. [PARIDE]
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 5a0c6ad..d90f831 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -46,3 +46,15 @@ config PCIEASPM_DEBUG
help
This enables PCI Express ASPM debug support. It will add per-device
interface to control ASPM.
+
+#
+# PCI Express ECRC
+#
+config PCIEECRC
+ bool "PCI Express ECRC support"
+ depends on PCI
+ help
+ Enables PCI Express ECRC (transaction layer end-to-end CRC
+ checking)
+
+ When in doubt, say N.
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 11f6bb1..acef212 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -5,6 +5,9 @@
# Build PCI Express ASPM if needed
obj-$(CONFIG_PCIEASPM) += aspm.o

+# Build PCI Express ECRC if needed
+obj-$(CONFIG_PCIEECRC) += ecrc.o
+
pcieportdrv-y := portdrv_core.o portdrv_pci.o portdrv_bus.o

obj-$(CONFIG_PCIEPORTBUS) += pcieportdrv.o
diff --git a/drivers/pci/pcie/ecrc.c b/drivers/pci/pcie/ecrc.c
new file mode 100644
index 0000000..eeb93df
--- /dev/null
+++ b/drivers/pci/pcie/ecrc.c
@@ -0,0 +1,94 @@
+/*
+ * Enables/disables PCIe ECRC checking.
+ *
+ * (C) Copyright 20009 Hewlett-Packard Development Company, L.P.
+ * Andrew Patterson <andrew.patterson@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/pci.h>
+#include <linux/pci_regs.h>
+#include <linux/errno.h>
+#include "../pci.h"
+
+#define ECRC_POLICY_DEFAULT 0 /* ECRC set by BIOS */
+#define ECRC_POLICY_OFF 1 /* ECRC off */
+#define ECRC_POLICY_ON 2 /* ECRC on */
+
+static int ecrc_policy = ECRC_POLICY_DEFAULT;
+
+static const char *ecrc_policy_str[] = {
+ [ECRC_POLICY_DEFAULT] = "default",
+ [ECRC_POLICY_OFF] = "off",
+ [ECRC_POLICY_ON] = "on"
+};
+
+/**
+ * pcie_set_ercr_checking - enable/disable PCIe ECRC checking
+ * @dev: the PCI device
+ *
+ * Returns 0 on success, or negative on failure.
+ */
+int pcie_set_ecrc_checking(struct pci_dev *dev)
+{
+ int pos;
+ u32 reg32;
+
+ if (!dev->is_pcie)
+ return -ENODEV;
+
+ /* Use firmware/BIOS setting if default */
+ if (ecrc_policy == ECRC_POLICY_DEFAULT)
+ return 0;
+
+ pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
+ if (!pos)
+ return -ENODEV;
+
+ pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
+ if (ecrc_policy == ECRC_POLICY_OFF) {
+ reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
+ } else if (ecrc_policy == ECRC_POLICY_ON) {
+ if (reg32 & PCI_ERR_CAP_ECRC_GENC)
+ reg32 |= PCI_ERR_CAP_ECRC_GENE;
+ if (reg32 & PCI_ERR_CAP_ECRC_CHKC)
+ reg32 |= PCI_ERR_CAP_ECRC_CHKE;
+ }
+ pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pcie_set_ecrc_checking);
+
+static int __init pcie_ecrc_get_policy(char *str)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ecrc_policy_str); i++)
+ if (!strncmp(str, ecrc_policy_str[i],
+ strlen(ecrc_policy_str[i])))
+ break;
+ if (i >= ARRAY_SIZE(ecrc_policy_str))
+ return 0;
+
+ ecrc_policy = i;
+ return 1;
+}
+__setup("pcie_ecrc=", pcie_ecrc_get_policy);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e2f3dd0..e2b0ab5 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -984,6 +984,9 @@ static void pci_init_capabilities(struct pci_dev *dev)

/* Single Root I/O Virtualization */
pci_iov_init(dev);
+
+ /* PCIe ECRC */
+ pcie_set_ecrc_checking(dev);
}

void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 507552d..080afd8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -879,6 +879,15 @@ static inline int pcie_aspm_enabled(void)
extern int pcie_aspm_enabled(void);
#endif

+#ifndef CONFIG_PCIEECRC
+static inline int pcie_set_ecrc_checking(struct pci_dev *dev)
+{
+ return 0;
+}
+#else
+extern int pcie_set_ecrc_checking(struct pci_dev *dev);
+#endif
+
#define pci_enable_msi(pdev) pci_enable_msi_block(pdev, 1)

#ifdef CONFIG_HT_IRQ

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