linux-kernel - [PATCH v2 3/3] staging: pi433: validate max bit

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Message-ID: <20220117060220.GA11202@mail.google.com>
Date:   Mon, 17 Jan 2022 19:02:20 +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 v2 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>
---
Meta-comments:

In the patchset v1 I kept bit_rate argument's original type as I thought that
changing it to accomodate values as high as 300kbps couldn't be part of this
patchset and therefore it should be a separate patchset. 

Given that kernel test bot compilation/test process 'complained' about the 
argument's type, I decided to send the v2 patch that addresses the data type
problem while I work on the patch that will change bit_rate type across
tx_cfg and rx_cfg as this will require a bit more work.

Please let me know if anyone dislikes the approach and wants me to deal with it
in a different way.
---
 drivers/staging/pi433/rf69.c | 14 ++++++++++++--
 drivers/staging/pi433/rf69.h |  2 +-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c
index f4ac17adcd83..adba69b8365e 100644
--- a/drivers/staging/pi433/rf69.c
+++ b/drivers/staging/pi433/rf69.c
@@ -223,15 +223,25 @@ int rf69_set_modulation_shaping(struct spi_device *spi,
 	}
 }
 
-int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate)
+int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate)
 {
 	int retval;
 	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 == FSK && bit_rate > 300000) ||
+	    (mod == OOK && bit_rate > 32768)) {
 		dev_dbg(&spi->dev, "setBitRate: illegal input param");
 		return -EINVAL;
 	}
diff --git a/drivers/staging/pi433/rf69.h b/drivers/staging/pi433/rf69.h
index c25942f142a6..3b8184155326 100644
--- a/drivers/staging/pi433/rf69.h
+++ b/drivers/staging/pi433/rf69.h
@@ -23,7 +23,7 @@ int rf69_set_data_mode(struct spi_device *spi, u8 data_mode);
 int rf69_set_modulation(struct spi_device *spi, enum modulation modulation);
 int rf69_set_modulation_shaping(struct spi_device *spi,
 				enum mod_shaping mod_shaping);
-int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate);
+int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate);
 int rf69_set_deviation(struct spi_device *spi, u32 deviation);
 int rf69_set_frequency(struct spi_device *spi, u32 frequency);
 int rf69_enable_amplifier(struct spi_device *spi, u8 amplifier_mask);
-- 
2.25.4