PCI: 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 "pci=ecrc=<policy>" command-line
option. If this option is not set or is set to 'bios", the enable and
generation bits are left in whatever state that firmware/BIOS set them to.
The "off" setting turns them off, and the "on" option turns them on (if the
device supports it).

Turning ECRC on or off can be a data integrity versus performance
tradeoff.  In theory, turning it on will catch more data errors, turning
it off means possibly better performance since CRC does not need to be
calculated by the PCIe hardware and packet sizes are reduced.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7bdaf5080408ad6e2e001eb0fb0cc8ad6636d0a0..395d1a013ebba455f477779ff86af062499b6900 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1824,6 +1824,12 @@ and is between 256 and 4096 characters. It is defined in the file
                                PAGE_SIZE is used as alignment.
                                PCI-PCI bridge can be specified, if resource
                                windows need to be expanded.
+               ecrc=           Enable/disable PCIe ECRC (transaction layer
+                               end-to-end CRC checking).
+                               bios: Use BIOS/firmware settings. This is the
+                               the default.
+                               off: Turn ECRC off
+                               on: Turn ECRC on.
 
        pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State Power
                        Management.

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 761557688b18db6b4bf4b7f99d0258df3a744ccd..56fb18d2cb521d09cc62b56a7e2e65d182c6607d 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2588,6 +2588,8 @@ static int __init pci_setup(char *str)
                        } else if (!strncmp(str, "resource_alignment=", 19)) {
                                pci_set_resource_alignment_param(str + 19,
                                                        strlen(str + 19));
+                       } else if (!strncmp(str, "ecrc=", 5)) {
+                               pcie_ecrc_get_policy(str + 5);
                        } else {
                                printk(KERN_ERR "PCI: Unknown option `%s'\n",
                                                str);

diff --git a/drivers/pci/pcie/aer/Kconfig b/drivers/pci/pcie/aer/Kconfig
index c3bde588aa13db4d814785ee24e7bfe86ef4c6c6..db4cb950933a555d9760fc7e83c000fb14e1776d 100644 (file)
--- a/drivers/pci/pcie/aer/Kconfig
+++ b/drivers/pci/pcie/aer/Kconfig
@@ -10,3 +10,16 @@ config PCIEAER
          This enables PCI Express Root Port Advanced Error Reporting
          (AER) driver support. Error reporting messages sent to Root
          Port will be handled by PCI Express AER driver.
+
+
+#
+# PCI Express ECRC
+#
+config PCIE_ECRC
+       bool "PCI Express ECRC settings control"
+       depends on PCIEAER
+       help
+         Used to override firmware/bios settings for PCI Express ECRC
+         (transaction layer end-to-end CRC checking).
+
+         When in doubt, say N.

diff --git a/drivers/pci/pcie/aer/Makefile b/drivers/pci/pcie/aer/Makefile
index 8da3bd8455a882b334cf8d843fa4846cc9153fe3..7f93411c56e5ad533bb05a755d2666a1735f118a 100644 (file)
--- a/drivers/pci/pcie/aer/Makefile
+++ b/drivers/pci/pcie/aer/Makefile
@@ -4,6 +4,8 @@
 
 obj-$(CONFIG_PCIEAER) += aerdriver.o
 
+obj-$(CONFIG_PCIE_ECRC)        += ecrc.o
+
 aerdriver-objs := aerdrv_errprint.o aerdrv_core.o aerdrv.o
 aerdriver-$(CONFIG_ACPI) += aerdrv_acpi.o
 

diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
index 307452f30035562cea6f290fb0fa1bac34679893..dd3829e68e3f0670d7ee3bead9138a899d54c12c 100644 (file)
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -113,15 +113,17 @@ static void set_device_error_reporting(struct pci_dev *dev, void *data)
 {
        bool enable = *((bool *)data);
 
-       if (dev->pcie_type != PCIE_RC_PORT &&
-           dev->pcie_type != PCIE_SW_UPSTREAM_PORT &&
-           dev->pcie_type != PCIE_SW_DOWNSTREAM_PORT)
-               return;
+       if (dev->pcie_type == PCIE_RC_PORT ||
+           dev->pcie_type == PCIE_SW_UPSTREAM_PORT ||
+           dev->pcie_type == PCIE_SW_DOWNSTREAM_PORT) {
+               if (enable)
+                       pci_enable_pcie_error_reporting(dev);
+               else
+                       pci_disable_pcie_error_reporting(dev);
+       }
 
        if (enable)
-               pci_enable_pcie_error_reporting(dev);
-       else
-               pci_disable_pcie_error_reporting(dev);
+               pcie_set_ecrc_checking(dev);
 }
 
 /**

diff --git a/drivers/pci/pcie/aer/ecrc.c b/drivers/pci/pcie/aer/ecrc.c
new file mode 100644 (file)
index 0000000..ece97df
--- /dev/null
+++ b/drivers/pci/pcie/aer/ecrc.c
@@ -0,0 +1,131 @@
+/*
+ *    Enables/disables PCIe ECRC checking.
+ *
+ *    (C) Copyright 2009 Hewlett-Packard Development Company, L.P.
+ *    Andrew Patterson <andrew.patterson@hp.com>
+ *
+ *    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 for performance */
+#define ECRC_POLICY_ON      2          /* ECRC on for data integrity */
+
+static int ecrc_policy = ECRC_POLICY_DEFAULT;
+
+static const char *ecrc_policy_str[] = {
+       [ECRC_POLICY_DEFAULT] = "bios",
+       [ECRC_POLICY_OFF] = "off",
+       [ECRC_POLICY_ON] = "on"
+};
+
+/**
+ * enable_ercr_checking - enable PCIe ECRC checking for a device
+ * @dev: the PCI device
+ *
+ * Returns 0 on success, or negative on failure.
+ */
+static int enable_ecrc_checking(struct pci_dev *dev)
+{
+       int pos;
+       u32 reg32;
+
+       if (!dev->is_pcie)
+               return -ENODEV;
+
+       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 (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;
+}
+
+/**
+ * disable_ercr_checking - disables PCIe ECRC checking for a device
+ * @dev: the PCI device
+ *
+ * Returns 0 on success, or negative on failure.
+ */
+static int disable_ecrc_checking(struct pci_dev *dev)
+{
+       int pos;
+       u32 reg32;
+
+       if (!dev->is_pcie)
+               return -ENODEV;
+
+       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);
+       reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
+       pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
+
+       return 0;
+}
+
+/**
+ * pcie_set_ecrc_checking - set/unset PCIe ECRC checking for a device based on global policy
+ * @dev: the PCI device
+ */
+void pcie_set_ecrc_checking(struct pci_dev *dev)
+{
+       switch (ecrc_policy) {
+       case ECRC_POLICY_DEFAULT:
+               return;
+       case ECRC_POLICY_OFF:
+               disable_ecrc_checking(dev);
+               break;
+       case ECRC_POLICY_ON:
+               enable_ecrc_checking(dev);;
+               break;
+       default:
+               return;
+       }
+}
+
+/**
+ * pcie_ecrc_get_policy - parse kernel command-line ecrc option
+ */
+void 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;
+
+       ecrc_policy = i;
+}

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 19ee92c53ef7dc11fb33660a995303d4404058aa..ec03b90d3510e87343dba3f1653b262d1924a8dc 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -878,6 +878,17 @@ static inline int pcie_aspm_enabled(void)
 extern int pcie_aspm_enabled(void);
 #endif
 
+#ifndef CONFIG_PCIE_ECRC
+static inline void pcie_set_ecrc_checking(struct pci_dev *dev)
+{
+       return;
+}
+static inline void pcie_ecrc_get_policy(char *str) {};
+#else
+extern void pcie_set_ecrc_checking(struct pci_dev *dev);
+extern void pcie_ecrc_get_policy(char *str);
+#endif
+
 #define pci_enable_msi(pdev)   pci_enable_msi_block(pdev, 1)
 
 #ifdef CONFIG_HT_IRQ