Hi Hector,

On Wed, 2021-10-06 at 00:59 +0900, Hector Martin wrote:

Implements genpd and reset providers for downstream devices. Each
instance of the driver binds to a single register and represents a
single SoC power domain.

The driver does not currently implement all features (auto-pm,
clockgate-only state), but we declare the respective registers for
documentation purposes. These features will be added as they become
useful for downstream devices.

This also creates the apple/soc tree and Kconfig submenu.

Signed-off-by: Hector Martin <redacted>
---
 MAINTAINERS                             |   1 +
 drivers/soc/Kconfig                     |   1 +
 drivers/soc/Makefile                    |   1 +
 drivers/soc/apple/Kconfig               |  21 ++
 drivers/soc/apple/Makefile              |   2 +
 drivers/soc/apple/apple-pmgr-pwrstate.c | 281 ++++++++++++++++++++++++
 6 files changed, 307 insertions(+)
 create mode 100644 drivers/soc/apple/Kconfig
 create mode 100644 drivers/soc/apple/Makefile
 create mode 100644 drivers/soc/apple/apple-pmgr-pwrstate.c

[...]

[...]

+static int apple_pmgr_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct apple_pmgr_ps *ps = rcdev_to_apple_pmgr_ps(rcdev);
+
+	mutex_lock(&ps->genpd.mlock);
+
+	if (ps->genpd.status == GENPD_STATE_OFF)
+		dev_err(ps->dev, "PS 0x%x: asserting RESET while powered down\n", ps->offset);
+
+	dev_dbg(ps->dev, "PS 0x%x: assert reset\n", ps->offset);
+	/* Quiesce device before asserting reset */
+	regmap_set_bits(ps->regmap, ps->offset, APPLE_PMGR_DEV_DISABLE);
+	regmap_set_bits(ps->regmap, ps->offset, APPLE_PMGR_RESET);
+
+	mutex_unlock(&ps->genpd.mlock);
+
+	return 0;
+}
+
+static int apple_pmgr_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct apple_pmgr_ps *ps = rcdev_to_apple_pmgr_ps(rcdev);
+
+	mutex_lock(&ps->genpd.mlock);
+
+	dev_dbg(ps->dev, "PS 0x%x: deassert reset\n", ps->offset);
+	regmap_clear_bits(ps->regmap, ps->offset, APPLE_PMGR_RESET);
+	regmap_clear_bits(ps->regmap, ps->offset, APPLE_PMGR_DEV_DISABLE);
+
+	if (ps->genpd.status == GENPD_STATE_OFF)
+		dev_err(ps->dev, "PS 0x%x: RESET was deasserted while powered down\n", ps->offset);
+
+	mutex_unlock(&ps->genpd.mlock);
+
+	return 0;
+}
+
+static int apple_pmgr_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	int ret;
+
+	ret = apple_pmgr_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	usleep_range(APPLE_PMGR_RESET_TIME, 2 * APPLE_PMGR_RESET_TIME);

Is this delay known to be long enough for all consumers using the
reset_control_reset() functionality? Are there any users at all?

Is it ok for a genpd transition to happen during this sleep?

+	return apple_pmgr_reset_deassert(rcdev, id);
+}

regards
Philipp

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