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From:   Naresh Solanki <naresh.solanki@9elements.com>
To:     devicetree@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
        Jean Delvare <jdelvare@suse.com>,
        Iwona Winiarska <iwona.winiarska@intel.com>
Cc:     linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
        Patrick Rudolph <patrick.rudolph@9elements.com>
Subject: [PATCH] hwmon: (dimmtemp) Support more than 32 DIMMs
Date:   Tue, 11 Jul 2023 17:21:43 +0200
Message-ID: <20230711152144.755177-1-Naresh.Solanki@9elements.com>
MIME-Version: 1.0
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From: Patrick Rudolph <patrick.rudolph@9elements.com>

This patch introduces support for handling more than 32 DIMMs by
utilizing bitmap operations. The changes ensure that the driver can
handle a higher number of DIMMs efficiently.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
---
 drivers/hwmon/peci/dimmtemp.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/hwmon/peci/dimmtemp.c b/drivers/hwmon/peci/dimmtemp.c
index ed968401f93c..ce89da3937a0 100644
--- a/drivers/hwmon/peci/dimmtemp.c
+++ b/drivers/hwmon/peci/dimmtemp.c
@@ -219,19 +219,21 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
 {
 	int chan_rank_max = priv->gen_info->chan_rank_max;
 	int dimm_idx_max = priv->gen_info->dimm_idx_max;
-	u32 chan_rank_empty = 0;
-	u32 dimm_mask = 0;
-	int chan_rank, dimm_idx, ret;
+	DECLARE_BITMAP(dimm_mask, DIMM_NUMS_MAX);
+	DECLARE_BITMAP(chan_rank_empty, CHAN_RANK_MAX);
+
+	int chan_rank, dimm_idx, ret, i;
 	u32 pcs;
 
-	BUILD_BUG_ON(BITS_PER_TYPE(chan_rank_empty) < CHAN_RANK_MAX);
-	BUILD_BUG_ON(BITS_PER_TYPE(dimm_mask) < DIMM_NUMS_MAX);
 	if (chan_rank_max * dimm_idx_max > DIMM_NUMS_MAX) {
 		WARN_ONCE(1, "Unsupported number of DIMMs - chan_rank_max: %d, dimm_idx_max: %d",
 			  chan_rank_max, dimm_idx_max);
 		return -EINVAL;
 	}
 
+	bitmap_zero(dimm_mask, DIMM_NUMS_MAX);
+	bitmap_zero(chan_rank_empty, CHAN_RANK_MAX);
+
 	for (chan_rank = 0; chan_rank < chan_rank_max; chan_rank++) {
 		ret = peci_pcs_read(priv->peci_dev, PECI_PCS_DDR_DIMM_TEMP, chan_rank, &pcs);
 		if (ret) {
@@ -242,7 +244,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
 			 * detection to be performed at a later point in time.
 			 */
 			if (ret == -EINVAL) {
-				chan_rank_empty |= BIT(chan_rank);
+				bitmap_set(chan_rank_empty, chan_rank, 1);
 				continue;
 			}
 
@@ -251,7 +253,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
 
 		for (dimm_idx = 0; dimm_idx < dimm_idx_max; dimm_idx++)
 			if (__dimm_temp(pcs, dimm_idx))
-				dimm_mask |= BIT(chan_rank * dimm_idx_max + dimm_idx);
+				bitmap_set(dimm_mask, chan_rank * dimm_idx_max + dimm_idx, 1);
 	}
 
 	/*
@@ -260,7 +262,7 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
 	 * host platform boot. Retrying a couple of times lets us make sure
 	 * that the state is persistent.
 	 */
-	if (chan_rank_empty == GENMASK(chan_rank_max - 1, 0)) {
+	if (bitmap_full(chan_rank_empty, chan_rank_max)) {
 		if (priv->no_dimm_retry_count < NO_DIMM_RETRY_COUNT_MAX) {
 			priv->no_dimm_retry_count++;
 
@@ -274,14 +276,16 @@ static int check_populated_dimms(struct peci_dimmtemp *priv)
 	 * It's possible that memory training is not done yet. In this case we
 	 * defer the detection to be performed at a later point in time.
 	 */
-	if (!dimm_mask) {
+	if (bitmap_empty(dimm_mask, DIMM_NUMS_MAX)) {
 		priv->no_dimm_retry_count = 0;
 		return -EAGAIN;
 	}
 
-	dev_dbg(priv->dev, "Scanned populated DIMMs: %#x\n", dimm_mask);
+	for_each_set_bit(i, dimm_mask, DIMM_NUMS_MAX) {
+		dev_dbg(priv->dev, "Found DIMM%#x\n", i);
+	}
 
-	bitmap_from_arr32(priv->dimm_mask, &dimm_mask, DIMM_NUMS_MAX);
+	bitmap_copy(priv->dimm_mask, dimm_mask, DIMM_NUMS_MAX);
 
 	return 0;
 }

base-commit: 4dbbaf8fbdbd13adc80731b2452257857e4c2d8b
-- 
2.41.0