linux-kernel - [PATCH v3 3/3] staging: pi433: validate max bit

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Date:   Wed, 19 Jan 2022 12:05:55 +1300
From:   Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@...il.com>
To:     gregkh@...uxfoundation.org, paulo.miguel.almeida.rodenas@...il.com,
        realwakka@...il.com
Cc:     linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v3 3/3] staging: pi433: validate max bit_rate based on
 modulation used

Max bit rate is dependent on which modulation is used. Previous
validation routine only took into consideration min bit rate which can
lead a misconfiguration of the rf69 chip causing the packets not to be
sent/read.

This patch enhances that input check in set_bit_rate to account for
modulation values and their respective max bit rate

Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@...il.com>
---
 drivers/staging/pi433/TODO   |  2 ++
 drivers/staging/pi433/rf69.c | 10 +++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/pi433/TODO b/drivers/staging/pi433/TODO
index 63a40bfcc67e..b9e6c01a02e0 100644
--- a/drivers/staging/pi433/TODO
+++ b/drivers/staging/pi433/TODO
@@ -3,3 +3,5 @@
 * currently the code introduces new IOCTLs. I'm afraid this is a bad idea.
   -> Replace this with another interface, hints are welcome!
 * Some missing data (marked with ###) needs to be added in the documentation
+* Change (struct pi433_tx_cfg)->bit_rate to be a u32 so that we can support
+    bit rates up to 300kbps per the spec.
diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c
index f4ac17adcd83..d60514a840c2 100644
--- a/drivers/staging/pi433/rf69.c
+++ b/drivers/staging/pi433/rf69.c
@@ -229,9 +229,17 @@ int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate)
 	u32 bit_rate_reg;
 	u8 msb;
 	u8 lsb;
+	enum modulation mod;
+
+	// check if modulation is configured
+	mod = rf69_get_modulation(spi);
+	if (mod == UNDEF) {
+		dev_dbg(&spi->dev, "setBitRate: modulation is undefined");
+		return -EINVAL;
+	}
 
 	// check input value
-	if (bit_rate < 1200) {
+	if (bit_rate < 1200 || (mod == OOK && bit_rate > 32768)) {
 		dev_dbg(&spi->dev, "setBitRate: illegal input param");
 		return -EINVAL;
 	}
-- 
2.25.4