libata-acpi: implement _GTF command filtering

Implement _GTF command filtering which can be controlled by
libata.acpi_filter kernel parameter.  Currently SETXFER and LOCK
commands are filtered.

libata configures transfer mode by itself and _GTF SETXFER commands
can potentially disrupt device configuration.  _GTM/_STM mechanism
can't handle hotplugging too well and when _GTF is executed,
controller is in PIO0 rather than the mode _STM configured.

Note that detecting SET MAX LOCK requires looking at the previous
command.  This adds a bit to code complexity.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 115 insertions, 44 deletions

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index d4cb557a727d..7bf4befd96bc 100644
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2006 Randy Dunlap
  */
 
+#include <linux/module.h>
 #include <linux/ata.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -25,6 +26,18 @@
 #include <acpi/acmacros.h>
 #include <acpi/actypes.h>
 
+enum {
+        ATA_ACPI_FILTER_SETXFER = 1 << 0,
+        ATA_ACPI_FILTER_LOCK    = 1 << 1,
+
+        ATA_ACPI_FILTER_DEFAULT = ATA_ACPI_FILTER_SETXFER |
+                                  ATA_ACPI_FILTER_LOCK,
+};
+
+static unsigned int ata_acpi_gtf_filter = ATA_ACPI_FILTER_DEFAULT;
+module_param_named(acpi_gtf_filter, ata_acpi_gtf_filter, int, 0644);
+MODULE_PARM_DESC(acpi_gtf_filter, "filter mask for ACPI _GTF commands, set to filter out (0x1=set xfermode, 0x2=lock/freeze lock)");
+
 #define NO_PORT_MULT            0xffff
 #define SATA_ADR(root, pmp)     (((root) << 16) | (pmp))
 
@@ -465,6 +478,60 @@ int ata_acpi_cbl_80wire(struct ata_port *ap)
 
 EXPORT_SYMBOL_GPL(ata_acpi_cbl_80wire);
 
+static void ata_acpi_gtf_to_tf(struct ata_device *dev,
+                               const struct ata_acpi_gtf *gtf,
+                               struct ata_taskfile *tf)
+{
+        ata_tf_init(dev, tf);
+
+        tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+        tf->protocol = ATA_PROT_NODATA;
+        tf->feature = gtf->tf[0];       /* 0x1f1 */
+        tf->nsect   = gtf->tf[1];       /* 0x1f2 */
+        tf->lbal    = gtf->tf[2];       /* 0x1f3 */
+        tf->lbam    = gtf->tf[3];       /* 0x1f4 */
+        tf->lbah    = gtf->tf[4];       /* 0x1f5 */
+        tf->device  = gtf->tf[5];       /* 0x1f6 */
+        tf->command = gtf->tf[6];       /* 0x1f7 */
+}
+
+static int ata_acpi_filter_tf(const struct ata_taskfile *tf,
+                              const struct ata_taskfile *ptf)
+{
+        if (ata_acpi_gtf_filter & ATA_ACPI_FILTER_SETXFER) {
+                /* libata doesn't use ACPI to configure transfer mode.
+                 * It will only confuse device configuration.  Skip.
+                 */
+                if (tf->command == ATA_CMD_SET_FEATURES &&
+                    tf->feature == SETFEATURES_XFER)
+                        return 1;
+        }
+
+        if (ata_acpi_gtf_filter & ATA_ACPI_FILTER_LOCK) {
+                /* BIOS writers, sorry but we don't wanna lock
+                 * features unless the user explicitly said so.
+                 */
+
+                /* DEVICE CONFIGURATION FREEZE LOCK */
+                if (tf->command == ATA_CMD_CONF_OVERLAY &&
+                    tf->feature == ATA_DCO_FREEZE_LOCK)
+                        return 1;
+
+                /* SECURITY FREEZE LOCK */
+                if (tf->command == ATA_CMD_SEC_FREEZE_LOCK)
+                        return 1;
+
+                /* SET MAX LOCK and SET MAX FREEZE LOCK */
+                if ((!ptf || ptf->command != ATA_CMD_READ_NATIVE_MAX) &&
+                    tf->command == ATA_CMD_SET_MAX &&
+                    (tf->feature == ATA_SET_MAX_LOCK ||
+                     tf->feature == ATA_SET_MAX_FREEZE_LOCK))
+                        return 1;
+        }
+
+        return 0;
+}
+
 /**
  * ata_acpi_run_tf - send taskfile registers to host controller
  * @dev: target ATA device
@@ -485,13 +552,15 @@ EXPORT_SYMBOL_GPL(ata_acpi_cbl_80wire);
  * EH context.
  *
  * RETURNS:
- * 1 if command is executed successfully.  0 if ignored or rejected,
- * -errno on other errors.
+ * 1 if command is executed successfully.  0 if ignored, rejected or
+ * filtered out, -errno on other errors.
  */
 static int ata_acpi_run_tf(struct ata_device *dev,
-                           const struct ata_acpi_gtf *gtf)
+                           const struct ata_acpi_gtf *gtf,
+                           const struct ata_acpi_gtf *prev_gtf)
 {
-        struct ata_taskfile tf, rtf;
+        struct ata_taskfile *pptf = NULL;
+        struct ata_taskfile tf, ptf, rtf;
         unsigned int err_mask;
         const char *level;
         char msg[60];
@@ -502,44 +571,44 @@ static int ata_acpi_run_tf(struct ata_device *dev,
             && (gtf->tf[6] == 0))
                 return 0;
 
-        ata_tf_init(dev, &tf);
-
-        /* convert gtf to tf */
-        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE; /* TBD */
-        tf.protocol = ATA_PROT_NODATA;
-        tf.feature = gtf->tf[0];        /* 0x1f1 */
-        tf.nsect   = gtf->tf[1];        /* 0x1f2 */
-        tf.lbal    = gtf->tf[2];        /* 0x1f3 */
-        tf.lbam    = gtf->tf[3];        /* 0x1f4 */
-        tf.lbah    = gtf->tf[4];        /* 0x1f5 */
-        tf.device  = gtf->tf[5];        /* 0x1f6 */
-        tf.command = gtf->tf[6];        /* 0x1f7 */
-
-        rtf = tf;
-        err_mask = ata_exec_internal(dev, &rtf, NULL, DMA_NONE, NULL, 0, 0);
-
-        switch (err_mask) {
-        case 0:
-                level = KERN_DEBUG;
-                snprintf(msg, sizeof(msg), "succeeded");
-                rc = 1;
-                break;
-
-        case AC_ERR_DEV:
+        ata_acpi_gtf_to_tf(dev, gtf, &tf);
+        if (prev_gtf) {
+                ata_acpi_gtf_to_tf(dev, prev_gtf, &ptf);
+                pptf = &ptf;
+        }
+
+        if (!ata_acpi_filter_tf(&tf, pptf)) {
+                rtf = tf;
+                err_mask = ata_exec_internal(dev, &rtf, NULL,
+                                             DMA_NONE, NULL, 0, 0);
+
+                switch (err_mask) {
+                case 0:
+                        level = KERN_DEBUG;
+                        snprintf(msg, sizeof(msg), "succeeded");
+                        rc = 1;
+                        break;
+
+                case AC_ERR_DEV:
+                        level = KERN_INFO;
+                        snprintf(msg, sizeof(msg),
+                                 "rejected by device (Stat=0x%02x Err=0x%02x)",
+                                 rtf.command, rtf.feature);
+                        rc = 0;
+                        break;
+
+                default:
+                        level = KERN_ERR;
+                        snprintf(msg, sizeof(msg),
+                                 "failed (Emask=0x%x Stat=0x%02x Err=0x%02x)",
+                                 err_mask, rtf.command, rtf.feature);
+                        rc = -EIO;
+                        break;
+                }
+        } else {
                 level = KERN_INFO;
-                snprintf(msg, sizeof(msg),
-                         "rejected by device (Stat=0x%02x Err=0x%02x)",
-                         rtf.command, rtf.feature);
+                snprintf(msg, sizeof(msg), "filtered out");
                 rc = 0;
-                break;
-
-        default:
-                level = KERN_ERR;
-                snprintf(msg, sizeof(msg),
-                         "failed (Emask=0x%x Stat=0x%02x Err=0x%02x)",
-                         err_mask, rtf.command, rtf.feature);
-                rc = -EIO;
-                break;
         }
 
         ata_dev_printk(dev, level,
@@ -566,7 +635,7 @@ static int ata_acpi_run_tf(struct ata_device *dev,
  */
 static int ata_acpi_exec_tfs(struct ata_device *dev, int *nr_executed)
 {
-        struct ata_acpi_gtf *gtf = NULL;
+        struct ata_acpi_gtf *gtf = NULL, *pgtf = NULL;
         int gtf_count, i, rc;
 
         /* get taskfiles */
@@ -576,12 +645,14 @@ static int ata_acpi_exec_tfs(struct ata_device *dev, int *nr_executed)
         gtf_count = rc;
 
         /* execute them */
-        for (i = 0; i < gtf_count; i++) {
-                rc = ata_acpi_run_tf(dev, gtf++);
+        for (i = 0; i < gtf_count; i++, gtf++) {
+                rc = ata_acpi_run_tf(dev, gtf, pgtf);
                 if (rc < 0)
                         break;
-                if (rc)
+                if (rc) {
                         (*nr_executed)++;
+                        pgtf = gtf;
+                }
         }
 
         ata_acpi_clear_gtf(dev);