From: Brad Bishop <bradleyb@xxxxxxxxxxxxxxxxxx> [ Upstream commit 0a35780c755ccec097d15c6b4ff8b246a89f1689 ] Make use of spi_max_transfer_size to avoid requesting transfers that are too large for some spi controllers. Signed-off-by: Brad Bishop <bradleyb@xxxxxxxxxxxxxxxxxx> Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx> Signed-off-by: Joel Stanley <joel@xxxxxxxxx> Link: https://lore.kernel.org/r/20220524215142.60047-1-eajames@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/misc/eeprom/at25.c | 93 ++++++++++++++++++++++---------------- 1 file changed, 53 insertions(+), 40 deletions(-) diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c index 8d169a35cf13..c9c56fd194c1 100644 --- a/drivers/misc/eeprom/at25.c +++ b/drivers/misc/eeprom/at25.c @@ -79,6 +79,11 @@ static int at25_ee_read(void *priv, unsigned int offset, { struct at25_data *at25 = priv; char *buf = val; + size_t max_chunk = spi_max_transfer_size(at25->spi); + size_t num_msgs = DIV_ROUND_UP(count, max_chunk); + size_t nr_bytes = 0; + unsigned int msg_offset; + size_t msg_count; u8 *cp; ssize_t status; struct spi_transfer t[2]; @@ -92,54 +97,59 @@ static int at25_ee_read(void *priv, unsigned int offset, if (unlikely(!count)) return -EINVAL; - cp = at25->command; + msg_offset = (unsigned int)offset; + msg_count = min(count, max_chunk); + while (num_msgs) { + cp = at25->command; - instr = AT25_READ; - if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR) - if (offset >= BIT(at25->addrlen * 8)) - instr |= AT25_INSTR_BIT3; + instr = AT25_READ; + if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR) + if (msg_offset >= BIT(at25->addrlen * 8)) + instr |= AT25_INSTR_BIT3; - mutex_lock(&at25->lock); + mutex_lock(&at25->lock); - *cp++ = instr; - - /* 8/16/24-bit address is written MSB first */ - switch (at25->addrlen) { - default: /* case 3 */ - *cp++ = offset >> 16; - fallthrough; - case 2: - *cp++ = offset >> 8; - fallthrough; - case 1: - case 0: /* can't happen: for better code generation */ - *cp++ = offset >> 0; - } + *cp++ = instr; - spi_message_init(&m); - memset(t, 0, sizeof(t)); + /* 8/16/24-bit address is written MSB first */ + switch (at25->addrlen) { + default: /* case 3 */ + *cp++ = msg_offset >> 16; + fallthrough; + case 2: + *cp++ = msg_offset >> 8; + fallthrough; + case 1: + case 0: /* can't happen: for better code generation */ + *cp++ = msg_offset >> 0; + } - t[0].tx_buf = at25->command; - t[0].len = at25->addrlen + 1; - spi_message_add_tail(&t[0], &m); + spi_message_init(&m); + memset(t, 0, sizeof(t)); - t[1].rx_buf = buf; - t[1].len = count; - spi_message_add_tail(&t[1], &m); + t[0].tx_buf = at25->command; + t[0].len = at25->addrlen + 1; + spi_message_add_tail(&t[0], &m); - /* - * Read it all at once. - * - * REVISIT that's potentially a problem with large chips, if - * other devices on the bus need to be accessed regularly or - * this chip is clocked very slowly. - */ - status = spi_sync(at25->spi, &m); - dev_dbg(&at25->spi->dev, "read %zu bytes at %d --> %zd\n", - count, offset, status); + t[1].rx_buf = buf + nr_bytes; + t[1].len = msg_count; + spi_message_add_tail(&t[1], &m); - mutex_unlock(&at25->lock); - return status; + status = spi_sync(at25->spi, &m); + + mutex_unlock(&at25->lock); + + if (status) + return status; + + --num_msgs; + msg_offset += msg_count; + nr_bytes += msg_count; + } + + dev_dbg(&at25->spi->dev, "read %zu bytes at %d\n", + count, offset); + return 0; } /* Read extra registers as ID or serial number */ @@ -190,6 +200,7 @@ ATTRIBUTE_GROUPS(sernum); static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count) { struct at25_data *at25 = priv; + size_t maxsz = spi_max_transfer_size(at25->spi); const char *buf = val; int status = 0; unsigned buf_size; @@ -253,6 +264,8 @@ static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count) segment = buf_size - (offset % buf_size); if (segment > count) segment = count; + if (segment > maxsz) + segment = maxsz; memcpy(cp, buf, segment); status = spi_write(at25->spi, bounce, segment + at25->addrlen + 1); -- 2.35.1
