ata: Prevent powering-off ATA hardwre if it reports as mSATA or m.2

As those form factors are typically not runtime removable and as such
expect to always being powered up.

This is an experimental change, and we might revert it if it doens't help

Change-Id: I61187f297866f64589a546352828a0ff8169fa30

firmware/drivers/ata.c

@@ -155,7 +155,8 @@ static inline bool ata_sleep_timed_out(void)
 static inline void schedule_ata_power_off(void)
 {
 #ifdef HAVE_ATA_POWER_OFF
-    power_off_tick = current_tick + ATA_POWER_OFF_TIMEOUT;
+    if (!ata_disk_can_poweroff())
+        power_off_tick = current_tick + ATA_POWER_OFF_TIMEOUT;
 #endif
 }
 
@@ -399,8 +400,8 @@ int ata_disk_isssd(void)
         However, this is a relatively recent change, and we can't rely on it,
         especially for the FC1307A CF->SD adapters!
 
-       Offset 167 is "Nominal Form Factor"
-        all values >= 0x06 are guaranteed to be solid State.
+       Offset 168 is "Nominal Form Factor"
+        all values >= 0x06 are guaranteed to be Solid State (mSATA, m.2, etc)
 
        Offset 83 b2 and/or 86 b2 is set to show device implementes CFA commands
 
@@ -414,6 +415,19 @@ int ata_disk_isssd(void)
             identify_info[217] == 0x0001 || identify_info[217] == 0x0100);
 }
 
+int ata_disk_can_poweroff(void)
+{
+    /* Some SSDs don't like getting powered off, presumably because
+       in the real world they're not in removable form factors and
+       don't expect to have power removed.
+
+       In particular, mSATA, m.2, and MicroSSD are suspect.
+    */
+
+    return ((identify_info[168] & 0x0f) < 0x06 ||
+            (identify_info[168] & 0x0f) > 0x08);
+}
+
 static int ata_transfer_sectors(unsigned long start,
                                 int incount,
                                 void* inbuf,

firmware/export/ata.h

@@ -168,6 +168,9 @@ int ata_spinup_time(void); /* ticks */
 /* Returns 1 if drive is solid-state */
 int ata_disk_isssd(void);
 
+/* Returns 1 if the drive can be powered off safely */
+int ata_disk_can_poweroff(void);
+
 #ifdef HAVE_ATA_DMA
 /* Returns current DMA mode */
 int ata_get_dma_mode(void);