lrdp-v2: mmcdoctor: Add support to extract mmc ring buffer.

Starting from sdm660(kernel version 4.4) mmc driver keeps last 64
mmc trace events in ring buffer.
This patch adds the support to extract it to mmcreport.txt
for both mmc0/mmc1.

Change-Id: I4b1d95106cbdd7262afe604a289ce2ebc59ccc52

linux-ramdump-parser-v2/parsers/mmcdoctor.py

@@ -30,6 +30,10 @@ PATTERN_END = "sdhci: ===================="
 MMC_DATA_HEAD = "#################### MMC(mmc%d) INFO START #######################\n"
 MMC_DATA_FOOT = "#################### MMC(mmc%d) INFO END #########################\n\n"
 
+MMC_TRACE_HEADER = "\n################ MMC(mmc%d) RING BUFFER ################\n"
+MMC_TRACE_BUF_EVENTS = 64
+MMC_TRACE_EVENT_SIZE = 256
+
 card_data = {
     0x2: "SANDISK",
     0x11: "TOSHIBA",
@@ -264,6 +268,43 @@ class MmcDataStructure():
         self.parse = ParseMmcLog(self.ramdump)
         return
 
+    def dump_trace_buf(self, fd):
+        if (not self.mmc_host or (fd <= 0) or (self.ramdump.kernel_version < (4, 4))):
+            return
+        mmc_host = self.mmc_host
+        ramdump = self.ramdump
+
+        fd.write(MMC_TRACE_HEADER % self.index)
+        buf_offset = ramdump.field_offset('struct mmc_host', 'trace_buf')
+        if (not buf_offset):
+            return 0
+
+        data_offset = ramdump.field_offset('struct mmc_trace_buffer', 'data')
+        if (not data_offset):
+            return 0
+
+        trace_buf = mmc_host + buf_offset
+        wr_idx = ramdump.read_int(trace_buf)
+        if (wr_idx >= 0xFFFFFFFF):
+            fd.write("mmc%d trace buffer empty\n" %(self.index))
+            return 0
+
+        dataptr = ramdump.read_word(trace_buf + data_offset)
+        if (not dataptr):
+            return
+
+        datastr = []
+        for i in xrange(MMC_TRACE_BUF_EVENTS):
+            trace_str = ramdump.read_cstring(dataptr, MMC_TRACE_EVENT_SIZE)
+            dataptr += MMC_TRACE_EVENT_SIZE
+            datastr.append(trace_str)
+        num = MMC_TRACE_BUF_EVENTS - 1
+        idx = wr_idx & num
+        cur_idx = (idx + 1) & num
+        for i in xrange(MMC_TRACE_BUF_EVENTS):
+            fd.write("event[%d] = %s" %(cur_idx, datastr[cur_idx]))
+            cur_idx = (cur_idx + 1 ) & num
+
     def dump_data(self, mode):
         fd = self.ramdump.open_file(F_MMCDEBUG, mode)
         fd.write(MMC_DATA_HEAD % self.index)
@@ -286,6 +327,7 @@ class MmcDataStructure():
         fd.write("Host ios_timing = %d\n" %self.hostinfo.ios_timing)
         fd.write("Host ios_signal_voltage = %d\n" %self.hostinfo.ios_signal_voltage)
         fd.write("Host ios_drv_type = %d\n" %self.hostinfo.ios_drv_type)
+        self.dump_trace_buf(fd)
         fd.write(MMC_DATA_FOOT % self.index)
         fd.close()
         return