[RESEND][PATCH][v2] ata: ahci: Add shutdown to freeze hardware resources of ahci

[Prabhakar Kushwaha]

device_shutdown() called from reboot or power_shutdown expect
all devices to be shutdown. Same is true for even ahci pci driver.
As no ahci shutdown function is implemented, the ata subsystem
always remains alive with DMA & interrupt support. File system 
related calls should not be honored after device_shutdown().

So defining ahci pci driver shutdown to freeze hardware (mask
interrupt, stop DMA engine and free DMA resources).

Signed-off-by: Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx>
---
- Resending with linux-kernel@xxxxxxxxxxxxxxx in CC
- Changes for v2: Incorporated Bjorn Helgaas's comments
   - Updated description
   - Removed Spurious whitespace change

Adding more details:
We are seeing an issue during kexec -e where SATA hard-disk is not
getting detected in second kernel. Lots of filesystem sync calls
can be seen even after device_shutdown(). 
Further invastigation revealed that pci_clear_master() causing this issue.
During device_shutdown() --> pci_device_shutdown() calls 
      --> ahci shutdown (not defined as of now, so device is still alive)
      --> pci_clear_master() 
pci_clear_master() disable DMA of device. Here filesystem calls after
device_shutdown() causing the issue. 

A device must implement shutdown() to stop/freeze before pcie_clear_master()
called from pci_device_shutdown(). Otherwise It can have weird effect.  
Refer  https://bugzilla.kernel.org/show_bug.cgi?id=63861#c24


 drivers/ata/ahci.c        |  7 +++++++
 drivers/ata/libata-core.c | 21 +++++++++++++++++++++
 include/linux/libata.h    |  1 +
 3 files changed, 29 insertions(+)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 4bfd1b14b390..11ea1aff40db 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -81,6 +81,7 @@ enum board_ids {
 
 static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
 static void ahci_remove_one(struct pci_dev *dev);
+static void ahci_shutdown_one(struct pci_dev *dev);
 static int ahci_vt8251_hardreset(struct ata_link *link, unsigned int *class,
 				 unsigned long deadline);
 static int ahci_avn_hardreset(struct ata_link *link, unsigned int *class,
@@ -606,6 +607,7 @@ static struct pci_driver ahci_pci_driver = {
 	.id_table		= ahci_pci_tbl,
 	.probe			= ahci_init_one,
 	.remove			= ahci_remove_one,
+	.shutdown		= ahci_shutdown_one,
 	.driver = {
 		.pm		= &ahci_pci_pm_ops,
 	},
@@ -1877,6 +1879,11 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	return 0;
 }
 
+static void ahci_shutdown_one(struct pci_dev *pdev)
+{
+	ata_pci_shutdown_one(pdev);
+}
+
 static void ahci_remove_one(struct pci_dev *pdev)
 {
 	pm_runtime_get_noresume(&pdev->dev);
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 6f4ab5c5b52d..42c8728f6117 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6767,6 +6767,26 @@ void ata_pci_remove_one(struct pci_dev *pdev)
 	ata_host_detach(host);
 }
 
+void ata_pci_shutdown_one(struct pci_dev *pdev)
+{
+	struct ata_host *host = pci_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < host->n_ports; i++) {
+		struct ata_port *ap = host->ports[i];
+
+		ap->pflags |= ATA_PFLAG_FROZEN;
+
+		/* Disable port interrupts */
+		if (ap->ops->freeze)
+			ap->ops->freeze(ap);
+
+		/* Stop the port DMA engines */
+		if (ap->ops->port_stop)
+			ap->ops->port_stop(ap);
+	}
+}
+
 /* move to PCI subsystem */
 int pci_test_config_bits(struct pci_dev *pdev, const struct pci_bits *bits)
 {
@@ -7387,6 +7407,7 @@ EXPORT_SYMBOL_GPL(ata_timing_cycle2mode);
 
 #ifdef CONFIG_PCI
 EXPORT_SYMBOL_GPL(pci_test_config_bits);
+EXPORT_SYMBOL_GPL(ata_pci_shutdown_one);
 EXPORT_SYMBOL_GPL(ata_pci_remove_one);
 #ifdef CONFIG_PM
 EXPORT_SYMBOL_GPL(ata_pci_device_do_suspend);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 2dbde119721d..bff539918d82 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1221,6 +1221,7 @@ struct pci_bits {
 };
 
 extern int pci_test_config_bits(struct pci_dev *pdev, const struct pci_bits *bits);
+extern void ata_pci_shutdown_one(struct pci_dev *pdev);
 extern void ata_pci_remove_one(struct pci_dev *pdev);
 
 #ifdef CONFIG_PM
-- 
2.17.1