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authorSheng Yang <sheng@linux.intel.com>2008-10-21 17:38:25 +0800
committerJesse Barnes <jbarnes@virtuousgeek.org>2008-10-22 16:42:35 -0700
commit8dd7f8036c123296fc4214f9d8810eb485570422 (patch)
tree0c6cab9083be724d2c72ba4aabef9e3b0dffd7fc /drivers/pci
parentc4ed02fae78bf6cea0b22edd34a67df972f29832 (diff)
downloadop-kernel-dev-8dd7f8036c123296fc4214f9d8810eb485570422.zip
op-kernel-dev-8dd7f8036c123296fc4214f9d8810eb485570422.tar.gz
PCI: add support for function level reset
Sometimes, it's necessary to enable software's ability to quiesce and reset endpoint hardware with function-level granularity, so provide support for it. The patch implement Function Level Reset(FLR) feature following PCI-e spec. And this is the first step. We would add more generic method, like D0/D3, to allow more devices support this function. The patch contains two functions. pcie_reset_function() is the new driver API, and, contains some action to quiesce a device. The other function is a helper: pcie_execute_reset_function() just executes the reset for a particular device function. Current the usage model is in KVM. Function reset is necessary for assigning device to a guest, or moving it between partitions. For Function Level Reset(FLR), please refer to PCI Express spec chapter 6.6.2. Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/pci.c98
1 files changed, 98 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index aee73cf..533aeb5 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -18,6 +18,7 @@
#include <linux/log2.h>
#include <linux/pci-aspm.h>
#include <linux/pm_wakeup.h>
+#include <linux/interrupt.h>
#include <asm/dma.h> /* isa_dma_bridge_buggy */
#include "pci.h"
@@ -1746,6 +1747,103 @@ EXPORT_SYMBOL(pci_set_dma_seg_boundary);
#endif
/**
+ * pci_execute_reset_function() - Reset a PCI device function
+ * @dev: Device function to reset
+ *
+ * Some devices allow an individual function to be reset without affecting
+ * other functions in the same device. The PCI device must be responsive
+ * to PCI config space in order to use this function.
+ *
+ * The device function is presumed to be unused when this function is called.
+ * Resetting the device will make the contents of PCI configuration space
+ * random, so any caller of this must be prepared to reinitialise the
+ * device including MSI, bus mastering, BARs, decoding IO and memory spaces,
+ * etc.
+ *
+ * Returns 0 if the device function was successfully reset or -ENOTTY if the
+ * device doesn't support resetting a single function.
+ */
+int pci_execute_reset_function(struct pci_dev *dev)
+{
+ u16 status;
+ u32 cap;
+ int exppos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+
+ if (!exppos)
+ return -ENOTTY;
+ pci_read_config_dword(dev, exppos + PCI_EXP_DEVCAP, &cap);
+ if (!(cap & PCI_EXP_DEVCAP_FLR))
+ return -ENOTTY;
+
+ pci_block_user_cfg_access(dev);
+
+ /* Wait for Transaction Pending bit clean */
+ msleep(100);
+ pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
+ if (status & PCI_EXP_DEVSTA_TRPND) {
+ dev_info(&dev->dev, "Busy after 100ms while trying to reset; "
+ "sleeping for 1 second\n");
+ ssleep(1);
+ pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
+ if (status & PCI_EXP_DEVSTA_TRPND)
+ dev_info(&dev->dev, "Still busy after 1s; "
+ "proceeding with reset anyway\n");
+ }
+
+ pci_write_config_word(dev, exppos + PCI_EXP_DEVCTL,
+ PCI_EXP_DEVCTL_BCR_FLR);
+ mdelay(100);
+
+ pci_unblock_user_cfg_access(dev);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pci_execute_reset_function);
+
+/**
+ * pci_reset_function() - quiesce and reset a PCI device function
+ * @dev: Device function to reset
+ *
+ * Some devices allow an individual function to be reset without affecting
+ * other functions in the same device. The PCI device must be responsive
+ * to PCI config space in order to use this function.
+ *
+ * This function does not just reset the PCI portion of a device, but
+ * clears all the state associated with the device. This function differs
+ * from pci_execute_reset_function in that it saves and restores device state
+ * over the reset.
+ *
+ * Returns 0 if the device function was successfully reset or -ENOTTY if the
+ * device doesn't support resetting a single function.
+ */
+int pci_reset_function(struct pci_dev *dev)
+{
+ u32 cap;
+ int exppos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ int r;
+
+ if (!exppos)
+ return -ENOTTY;
+ pci_read_config_dword(dev, exppos + PCI_EXP_DEVCAP, &cap);
+ if (!(cap & PCI_EXP_DEVCAP_FLR))
+ return -ENOTTY;
+
+ if (!dev->msi_enabled && !dev->msix_enabled)
+ disable_irq(dev->irq);
+ pci_save_state(dev);
+
+ pci_write_config_word(dev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
+
+ r = pci_execute_reset_function(dev);
+
+ pci_restore_state(dev);
+ if (!dev->msi_enabled && !dev->msix_enabled)
+ enable_irq(dev->irq);
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(pci_reset_function);
+
+/**
* pcix_get_max_mmrbc - get PCI-X maximum designed memory read byte count
* @dev: PCI device to query
*
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