linux-kernel - [PATCH v3 4/5] w1: ds2433: use the kernel bitmap implementation

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Message-Id: <20231130135232.191320-5-marc.ferland@sonatest.com>
Date:   Thu, 30 Nov 2023 08:52:31 -0500
From:   marc.ferland@...il.com
To:     krzysztof.kozlowski@...aro.org
Cc:     gregkh@...uxfoundation.org, marc.ferland@...atest.com,
        jeff.dagenais@...il.com, rdunlap@...radead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 4/5] w1: ds2433: use the kernel bitmap implementation

From: Marc Ferland <marc.ferland@...atest.com>

The ds2433 driver uses the 'validcrc' variable to mark out which pages
have been successfully (crc is valid) retrieved from the eeprom and
placed in the internal 'memory' buffer (see CONFIG_W1_SLAVE_DS2433_CRC).

The current implementation assumes that the number of pages will never
go beyond 32 pages (bit field is a u32). This is fine for the ds2433
since it only has 16 pages.

Use a dynamically allocated bitmap so that we can support eeproms with
more than 32 pages which is the case for the ds28ec20 (80 pages).

As an added bonus, the code also gets easier on the eye.

Signed-off-by: Marc Ferland <marc.ferland@...atest.com>
---
 drivers/w1/slaves/w1_ds2433.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/w1/slaves/w1_ds2433.c b/drivers/w1/slaves/w1_ds2433.c
index 7d4d9fc1a9c4..63ed03191137 100644
--- a/drivers/w1/slaves/w1_ds2433.c
+++ b/drivers/w1/slaves/w1_ds2433.c
@@ -49,8 +49,8 @@ static const struct ds2433_config config_f23 = {
 
 struct w1_f23_data {
 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
-	u8	*memory;
-	u32	validcrc;
+	u8		*memory;
+	unsigned long	*validcrc;
 #endif
 	const struct ds2433_config *cfg;
 };
@@ -77,11 +77,11 @@ static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
 	u8	wrbuf[3];
 	int	off = block * W1_PAGE_SIZE;
 
-	if (data->validcrc & (1 << block))
+	if (test_bit(block, data->validcrc))
 		return 0;
 
 	if (w1_reset_select_slave(sl)) {
-		data->validcrc = 0;
+		bitmap_zero(data->validcrc, data->cfg->page_count);
 		return -EIO;
 	}
 
@@ -93,7 +93,7 @@ static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
 
 	/* cache the block if the CRC is valid */
 	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
-		data->validcrc |= (1 << block);
+		set_bit(block, data->validcrc);
 
 	return 0;
 }
@@ -208,7 +208,7 @@ static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 	/* Reset the bus to wake up the EEPROM (this may not be needed) */
 	w1_reset_bus(sl->master);
 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
-	f23->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
+	clear_bit(addr >> W1_PAGE_BITS, f23->validcrc);
 #endif
 	return 0;
 }
@@ -296,6 +296,13 @@ static int w1_f23_add_slave(struct w1_slave *sl)
 		kfree(data);
 		return -ENOMEM;
 	}
+	data->validcrc = bitmap_zalloc(data->cfg->page_count,
+				       GFP_KERNEL);
+	if (!data->validcrc) {
+		kfree(data->memory);
+		kfree(data);
+		return -ENOMEM;
+	}
 #endif /* CONFIG_W1_SLAVE_DS2433_CRC */
 	sl->family_data = data;
 
@@ -307,6 +314,7 @@ static void w1_f23_remove_slave(struct w1_slave *sl)
 	struct w1_f23_data *data = sl->family_data;
 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
 	kfree(data->memory);
+	bitmap_free(data->validcrc);
 #endif /* CONFIG_W1_SLAVE_DS2433_CRC */
 	kfree(data);
 	sl->family_data = NULL;
-- 
2.34.1