linux-kernel - [PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

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Message-ID: <ca76e2bb2f5d47ad189fa1a40bb6dd8a5dc225d2.1650606541.git.helmut.grohne@intenta.de>
Date:   Fri, 22 Apr 2022 08:16:31 +0200
From:   Helmut Grohne <helmut.grohne@...enta.de>
To:     Support Opensource <support.opensource@...semi.com>,
        Lee Jones <lee.jones@...aro.org>
CC:     <linux-kernel@...r.kernel.org>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        Mark Brown <broonie@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: [PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

The DA9062 can be the device used to power the CPU. In that case, it can
be used to power off the system. In the CONTROL_A register, the M_*_EN
bits must be zero for the corresponding *_EN bits to have an effect. We
zero them all to turn off the system.

Signed-off-by: Helmut Grohne <helmut.grohne@...enta.de>
---
 drivers/mfd/da9062-core.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

This series effectively is a rebased resend. The earlier posting was
https://lore.kernel.org/all/20200107120559.GA700@laureti-dev/. At that time,
Adam Thomson critisized the use of regmap and i2c inside a pm_power_off hook
since irqs are disabled. He reached out to Lee Jones, who asked Mark Brown and
Wolfram Sang, but never got any reply. I noted that a fair number of other
drivers do use regmap and i2c despite this issue. In the mean time, more
instances were added:
 * drivers/mfd/acer-ec-a500.c uses i2c
 * drivers/mfd/ntxec.c uses i2c
 * drivers/mfd/rk808.c uses regmap and i2c
Given that we proceeded with accepting the use of i2c and regmap inside
pm_power_off hooks, I think we can proceed with this patch as well.

Helmut

diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c
index 2774b2cbaea6..e7af5b5f16e0 100644
--- a/drivers/mfd/da9062-core.c
+++ b/drivers/mfd/da9062-core.c
@@ -620,6 +620,23 @@ static const struct of_device_id da9062_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, da9062_dt_ids);

+/* Hold client since pm_power_off is global. */
+static struct i2c_client *da9062_i2c_client;
+
+static void da9062_power_off(void)
+{
+	struct da9062 *chip = i2c_get_clientdata(da9062_i2c_client);
+	const unsigned int mask = DA9062AA_SYSTEM_EN_MASK |
+		DA9062AA_POWER_EN_MASK | DA9062AA_POWER1_EN_MASK |
+		DA9062AA_M_SYSTEM_EN_MASK | DA9062AA_M_POWER_EN_MASK |
+		DA9062AA_M_POWER1_EN_MASK;
+	int ret = regmap_update_bits(chip->regmap, DA9062AA_CONTROL_A, mask, 0);
+
+	if (ret < 0)
+		dev_err(&da9062_i2c_client->dev,
+			"DA9062AA_CONTROL_A update failed, %d\n", ret);
+}
+
 static int da9062_i2c_probe(struct i2c_client *i2c,
 	const struct i2c_device_id *id)
 {
@@ -720,6 +737,15 @@ static int da9062_i2c_probe(struct i2c_client *i2c,
 		return ret;
 	}

+	if (of_device_is_system_power_controller(i2c->dev.of_node)) {
+		if (!pm_power_off) {
+			da9062_i2c_client = i2c;
+			pm_power_off = da9062_power_off;
+		} else {
+			dev_warn(&i2c->dev, "Poweroff callback already assigned\n");
+		}
+	}
+
 	return ret;
 }

@@ -727,6 +753,11 @@ static int da9062_i2c_remove(struct i2c_client *i2c)
 {
 	struct da9062 *chip = i2c_get_clientdata(i2c);

+	if (pm_power_off == da9062_power_off)
+		pm_power_off = NULL;
+	if (da9062_i2c_client)
+		da9062_i2c_client = NULL;
+
 	mfd_remove_devices(chip->dev);
 	regmap_del_irq_chip(i2c->irq, chip->regmap_irq);

-- 
2.20.1

Dipl.-Inf. Helmut Grohne
Research and Development
Application Engineering

Phone: +49 (371) 24354 0 ∙ Fax:  +49 (371) 24354 020
helmut.grohne@...enta.de ∙ https://www.intenta.de

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