kernel/wr_pstats: get rid of userv

Apply zero bias at every read from FPGA.

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>

kernel/wr_pstats/wr_pstats.c

@@ -116,7 +116,6 @@ struct cntrs_dev {
 	/* there is no need to keep 64bits for zero values,
 	 * part which is read from FPGA is enough */
 	uint16_t zeros[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
-	uint64_t userv[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
 	struct PSTATS_WB __iomem *regs;
 
 	/* prevents from simultaneous access to cntrs array from tasklet and
@@ -286,6 +285,10 @@ static int rd_cnt_word(int port, int adr)
 		ptr = &(pstats_dev.cntrs[port][4 * adr + i]);
 		*ptr &= PSTATS_MSB_MSK;
 		*ptr |= hwcnt_to_sw(val[0], val[1], i);
+		/* apply zero bias,
+		 * NOTE: since cntrs are monotonic, they're always bigger than
+		 * zeros */
+		*ptr -= pstats_dev.zeros[port][4 * adr + i];
 		spin_unlock(&pstats_dev.port_mutex[port]);
 	}
 
@@ -308,11 +311,16 @@ static void pstats_zero(int port)
 	pstats_rd_cntrs(port);
 	spin_lock(&pstats_dev.port_mutex[port]);
 	for (i = 0; i < PSTATS_MAX_NUM_OF_COUNTERS; i++) {
+		/* since cntrs is monotonic it will never happen that zero will
+		 * be bigger than cntrs */
+		/* add zeros since it was substracted before in
+		 * pstats_rd_cntrs (rd_cnt_word) */
+		pstats_dev.cntrs[port][i] += pstats_dev.zeros[port][i];
+		/* clear 48 MSBits */
+		pstats_dev.cntrs[port][i] &= PSTATS_LSB_MSK;
 		/* Copy 16 LSBits to zero */
 		pstats_dev.zeros[port][i] =
 			(uint16_t) pstats_dev.cntrs[port][i];
-		/* clear 48 MSBits */
-		pstats_dev.cntrs[port][i] &= PSTATS_LSB_MSK;
 	}
 	spin_unlock(&pstats_dev.port_mutex[port]);
 }
@@ -340,8 +348,8 @@ static int pstats_desc_handler(ctl_table *ctl, int write, void *buffer,
 static int pstats_handler(ctl_table *ctl, int write, void *buffer,
 		size_t *lenp, loff_t *ppos)
 {
-	int i, port;
-	struct cntrs_dev *d = &pstats_dev;
+	int port;
+	int ret;
 
 	port = (int)ctl->extra1;
 
@@ -357,18 +365,23 @@ static int pstats_handler(ctl_table *ctl, int write, void *buffer,
 	}
 
 	if (port < pstats_nports) {
+		/* read counters including correction of zeros offset */
 		pstats_rd_cntrs(port);
-		for (i = 0; i < firmware_counters; i++)
-			d->userv[port][i] = d->cntrs[port][i] - d->zeros[port][i];
 	} else {
 		/* stuff for info file, read at module load time */
 		pstats_info[PINFO_VER] = firmware_version;
 		pstats_info[PINFO_CNTPW] = firmware_cpw;
 		pstats_info[PINFO_CNTPP] = firmware_counters;
 	}
+	/* It might happen that irq comes between reading MSB 32 bits and
+	 * LSB 32 bits of particualr counter.
+	 * In that case counter's value would be lower than previous one */
+	spin_lock(&pstats_dev.port_mutex[port]);
 	/* each value will be split into two unsigned longs,
 	 * each counter has to be assembled in software reading pstats */
-	return proc_dointvec(ctl, 0, buffer, lenp, ppos);
+	ret = proc_dointvec(ctl, 0, buffer, lenp, ppos);
+	spin_unlock(&pstats_dev.port_mutex[port]);
+	return ret;
 }
 
 /* one per port, then info and description, and terminator, filled at init time */
@@ -470,7 +483,7 @@ static int __init pstats_init(void)
 
 	for (i = 0; i < pstats_nports; ++i) {
 		pstats_ctl_table[i].procname = portnames[i];
-		pstats_ctl_table[i].data = &pstats_dev.userv[i];
+		pstats_ctl_table[i].data = &pstats_dev.cntrs[i];
 		/* each value will be split into two unsigned longs,
 		 * each counter has to be assembled in software reading pstats
 		 */