linux-kernel - [PATCH 2/2] ASoC: cs35l56: Don't overwrite a patched firmware

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Date:   Tue, 15 Aug 2023 13:48:26 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 2/2] ASoC: cs35l56: Don't overwrite a patched firmware

Only attempt to download wmfw/bin files to a non-secured part if
it reports FIRMWARE_MISSING. If FIRMWARE_MISSING is false the
firmware has already been patched and overwriting the patch could
corrupt the running firmware.

For a secured part the wmfw/bin can be downloaded even if
FIRMWARE_MISSING is false, because they will only patch tunings.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 sound/soc/codecs/cs35l56.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/cs35l56.c b/sound/soc/codecs/cs35l56.c
index 98cfcae554af..3a9ec8724cc1 100644
--- a/sound/soc/codecs/cs35l56.c
+++ b/sound/soc/codecs/cs35l56.c
@@ -665,8 +665,17 @@ static void cs35l56_secure_patch(struct cs35l56_private *cs35l56)
 
 static void cs35l56_patch(struct cs35l56_private *cs35l56)
 {
+	unsigned int firmware_missing;
 	int ret;
 
+	ret = regmap_read(cs35l56->base.regmap, CS35L56_PROTECTION_STATUS, &firmware_missing);
+	if (ret) {
+		dev_err(cs35l56->base.dev, "Failed to read PROTECTION_STATUS: %d\n", ret);
+		return;
+	}
+
+	firmware_missing &= CS35L56_FIRMWARE_MISSING;
+
 	/*
 	 * Disable SoundWire interrupts to prevent race with IRQ work.
 	 * Setting sdw_irq_no_unmask prevents the handler re-enabling
@@ -685,8 +694,12 @@ static void cs35l56_patch(struct cs35l56_private *cs35l56)
 	if (ret)
 		goto err;
 
-	/* Use wm_adsp to load and apply the firmware patch and coefficient files */
-	ret = wm_adsp_power_up(&cs35l56->dsp, true);
+	/*
+	 * Use wm_adsp to load and apply the firmware patch and coefficient files,
+	 * but only if firmware is missing. If firmware is already patched just
+	 * power-up wm_adsp without downloading firmware.
+	 */
+	ret = wm_adsp_power_up(&cs35l56->dsp, !!firmware_missing);
 	if (ret) {
 		dev_dbg(cs35l56->base.dev, "%s: wm_adsp_power_up ret %d\n", __func__, ret);
 		goto err;
-- 
2.30.2