[PATCH 6.8 658/715] spi: spi-mem: add statistics support to ->exec_op() calls

Sasha Levin
2024-03-24T22:45:51Z

From: Théo Lebrun <theo.lebrun@bootlin.com>

[ Upstream commit e63aef9c9121e5061cbf5112d12cadc9da399692 ]

Current behavior is that spi-mem operations do not increment statistics,
neither per-controller nor per-device, if ->exec_op() is used. For
operations that do NOT use ->exec_op(), stats are increased as the
usual spi_sync() is called.

The newly implemented spi_mem_add_op_stats() function is strongly
inspired by spi_statistics_add_transfer_stats(); locking logic and
l2len computation comes from there.

Statistics that are being filled: bytes{,_rx,_tx}, messages, transfers,
errors, timedout, transfer_bytes_histo_*.

Note about messages & transfers counters: in the fallback to spi_sync()
case, there are from 1 to 4 transfers per message. We only register one
big transfer in the ->exec_op() case as that is closer to reality.

This patch is NOT touching:
- spi_async, spi_sync, spi_sync_immediate: those counters describe
precise function calls, incrementing them would be lying. I believe
comparing the messages counter to spi_async+spi_sync is a good way
to detect ->exec_op() calls, but I might be missing edge cases
knowledge.
- transfers_split_maxsize: splitting cannot happen if ->exec_op() is
provided.

Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://msgid.link/r/20240216-spi-mem-stats-v2-1-9256dfe4887d@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: 29895ce18311 ("spi: Fix error code checking in spi_mem_exec_op()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-mem.c | 49 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 2dc8ceb85374b..c9d6d42a88f55 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -297,6 +297,49 @@ static void spi_mem_access_end(struct spi_mem *mem)
pm_runtime_put(ctlr->dev.parent);
}

+static void spi_mem_add_op_stats(struct spi_statistics __percpu *pcpu_stats,
+ const struct spi_mem_op *op, int exec_op_ret)
+{
+ struct spi_statistics *stats;
+ u64 len, l2len;
+
+ get_cpu();
+ stats = this_cpu_ptr(pcpu_stats);
+ u64_stats_update_begin(&stats->syncp);
+
+ /*
+ * We do not have the concept of messages or transfers. Let's consider
+ * that one operation is equivalent to one message and one transfer.
+ */
+ u64_stats_inc(&stats->messages);
+ u64_stats_inc(&stats->transfers);
+
+ /* Use the sum of all lengths as bytes count and histogram value. */
+ len = op->cmd.nbytes + op->addr.nbytes;
+ len += op->dummy.nbytes + op->data.nbytes;
+ u64_stats_add(&stats->bytes, len);
+ l2len = min(fls(len), SPI_STATISTICS_HISTO_SIZE) - 1;
+ u64_stats_inc(&stats->transfer_bytes_histo[l2len]);
+
+ /* Only account for data bytes as transferred bytes. */
+ if (op->data.nbytes && op->data.dir == SPI_MEM_DATA_OUT)
+ u64_stats_add(&stats->bytes_tx, op->data.nbytes);
+ if (op->data.nbytes && op->data.dir == SPI_MEM_DATA_IN)
+ u64_stats_add(&stats->bytes_rx, op->data.nbytes);
+
+ /*
+ * A timeout is not an error, following the same behavior as
+ * spi_transfer_one_message().
+ */
+ if (exec_op_ret == -ETIMEDOUT)
+ u64_stats_inc(&stats->timedout);
+ else if (exec_op_ret)
+ u64_stats_inc(&stats->errors);
+
+ u64_stats_update_end(&stats->syncp);
+ put_cpu();
+}
+
/**
* spi_mem_exec_op() - Execute a memory operation
* @mem: the SPI memory
@@ -339,8 +382,12 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
* read path) and expect the core to use the regular SPI
* interface in other cases.
*/
- if (!ret || ret != -ENOTSUPP || ret != -EOPNOTSUPP)
+ if (!ret || ret != -ENOTSUPP || ret != -EOPNOTSUPP) {
+ spi_mem_add_op_stats(ctlr->pcpu_statistics, op, ret);
+ spi_mem_add_op_stats(mem->spi->pcpu_statistics, op, ret);
+
return ret;
+ }
}

tmpbufsize = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
--
2.43.0