linux-kernel - [PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

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Date:   Wed,  4 Jan 2023 18:36:29 +0900
From:   Hector Martin <marcan@...can.st>
To:     Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        Janne Grunau <j@...nau.net>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        asahi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Hector Martin <marcan@...can.st>
Subject: [PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

From: Janne Grunau <j@...nau.net>

65us is not a reasonable maximum for this property, as some devices
might need a much longer setup time (e.g. those driven by firmware on
the other end). Plus, device tree property values are in 32-bit cells
and smaller widths should not be used without good reason.

Also move the logic to a helper function, since this will later be used
to parse other CS delay properties too.

Fixes: 33a2fde5f77b ("spi: Introduce spi-cs-setup-ns property")
Signed-off-by: Janne Grunau <j@...nau.net>
Signed-off-by: Hector Martin <marcan@...can.st>
---
 drivers/spi/spi.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 15f174f4e056..370e4c85dc54 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2220,6 +2220,22 @@ void spi_flush_queue(struct spi_controller *ctlr)
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_OF)
+static void of_spi_parse_dt_cs_delay(struct device_node *nc,
+				     struct spi_delay *delay, const char *prop)
+{
+	u32 value;
+
+	if (!of_property_read_u32(nc, prop, &value)) {
+		if (value > U16_MAX) {
+			delay->value = DIV_ROUND_UP(value, 1000);
+			delay->unit = SPI_DELAY_UNIT_USECS;
+		} else {
+			delay->value = value;
+			delay->unit = SPI_DELAY_UNIT_NSECS;
+		}
+	}
+}
+
 static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 			   struct device_node *nc)
 {
@@ -2310,10 +2326,8 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
 		spi->max_speed_hz = value;
 
-	if (!of_property_read_u16(nc, "spi-cs-setup-delay-ns", &cs_setup)) {
-		spi->cs_setup.value = cs_setup;
-		spi->cs_setup.unit = SPI_DELAY_UNIT_NSECS;
-	}
+	/* Device CS delays */
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_setup, "spi-cs-setup-delay-ns");
 
 	return 0;
 }
-- 
2.35.1