linux-kernel - [PATCH] regulator: bd718x7: Change next state after poweroff to ready

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Date:   Wed, 7 Nov 2018 15:41:26 +0200
From:   Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, mazziesaccount@...il.com
Cc:     linux-kernel@...r.kernel.org, heikki.haikola@...rohmeurope.com,
        mikko.mutanen@...rohmeurope.com
Subject: [PATCH] regulator: bd718x7: Change next state after poweroff to ready

BD71837 and BD71847 have a HW functionality which leave power
rails OFF after powerof state:
- if they have been controlled by SW.
- if state transition from poweroff is done to SNVS

BD71837 can after reset transition from power-off to SNVS or
READY state depending on reset reason. By default only wathcdog
reset changes state from poweroff to ready. Change PMIC
configuration to always transition to READY in order to avoid
crucial power rails being OFF after reset.

If SNVS is required the crucial power rails should not be
controlled by SW - eg corresponding regulator control register
should have SEL bit kept zero. Currently the driver assumes all
regulators to be controlled by SW so it sets all SEL bits to 1.

Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
---
 drivers/regulator/bd718x7-regulator.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/regulator/bd718x7-regulator.c b/drivers/regulator/bd718x7-regulator.c
index 3a47e0372e77..63669f9038cc 100644
--- a/drivers/regulator/bd718x7-regulator.c
+++ b/drivers/regulator/bd718x7-regulator.c
@@ -1053,6 +1053,29 @@ static int bd718xx_probe(struct platform_device *pdev)
 			BD718XX_REG_REGLOCK);
 	}
 
+	/* At poweroff transition PMIC HW disables EN bit for regulators but
+	 * leaves SEL bit untouched. So if state transition from POWEROFF
+	 * is done to SNVS - then all power rails controlled by SW (having
+	 * SEL bit set) stay disabled as EN is cleared. This may result boot
+	 * failure if any crucial systems are powered by these rails.
+	 *
+	 * Change the next stage from poweroff to be READY instead of SNVS
+	 * for all reset types because OTP loading at READY will clear SEL
+	 * bit allowing HW defaults for power rails to be used
+	 */
+	err = regmap_update_bits(mfd->regmap, BD718XX_REG_TRANS_COND1,
+				 BD718XX_ON_REQ_POWEROFF_MASK |
+				 BD718XX_SWRESET_POWEROFF_MASK |
+				 BD718XX_WDOG_POWEROFF_MASK |
+				 BD718XX_KEY_L_POWEROFF_MASK,
+				 BD718XX_POWOFF_TO_RDY);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to change reset target\n");
+		goto err;
+	} else {
+		dev_dbg(&pdev->dev, "Changed all resets from SVNS to READY\n");
+	}
+
 	for (i = 0; i < pmic_regulators[mfd->chip_type].r_amount; i++) {
 
 		const struct regulator_desc *desc;
-- 
2.14.3