kernel/wr_pstats: reduce size of zeros from 64bit to 16bit

zeros keep only value read from FPGA at zeroing. The rest can be zeroed simply
in software.

Change the size of cntrs and userv from unsigned long long to uint64_t.

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

kernel/wr_pstats/wr_pstats.c

@@ -112,9 +112,11 @@ static struct pstats_version_description pstats_desc[] = {
 };
 
 struct cntrs_dev {
-	unsigned long long cntrs[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
-	unsigned long long zeros[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
-	unsigned long long userv[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
+	uint64_t cntrs[PSTATS_MAX_NPORTS][PSTATS_MAX_NUM_OF_COUNTERS];
+	/* 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
@@ -185,7 +187,7 @@ static void pstats_tlet_fn(unsigned long arg)
 	uint32_t irqs;
 	uint64_t *cntrs_ov;
 	int port, cntr;
-	unsigned long long *ptr;
+	uint64_t *ptr;
 	struct cntrs_dev *device = (struct cntrs_dev *)arg;
 
 	if (device->irqs_head - device->irqs_tail > PSTATS_IRQBUFSZ) {
@@ -266,7 +268,7 @@ static irqreturn_t pstats_irq_handler(int irq, void *devid)
 static int rd_cnt_word(int port, int adr)
 {
 	uint32_t val[2];
-	unsigned long long *ptr;
+	uint64_t *ptr;
 	int i;
 
 	val[0] = (adr<<PSTATS_CR_ADDR_SHIFT |
@@ -302,11 +304,16 @@ static int pstats_rd_cntrs(int port)
 
 static void pstats_zero(int port)
 {
+	int i;
 	pstats_rd_cntrs(port);
 	spin_lock(&pstats_dev.port_mutex[port]);
-	memcpy(pstats_dev.zeros[port],
-	       pstats_dev.cntrs[port],
-	       sizeof(pstats_dev.zeros[port]));
+	for (i = 0; i < PSTATS_MAX_NUM_OF_COUNTERS; i++) {
+		/* 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]);
 }
 
@@ -468,7 +475,7 @@ static int __init pstats_init(void)
 		 * each counter has to be assembled in software reading pstats
 		 */
 		pstats_ctl_table[i].maxlen =
-			firmware_counters*sizeof(unsigned long long);
+			firmware_counters*sizeof(uint64_t);
 		pstats_ctl_table[i].mode = 0644;
 		pstats_ctl_table[i].proc_handler = pstats_handler;
 		pstats_ctl_table[i].extra1 = (void *)i;