soc: imx: add i.MX8M blk-ctrl driver

This adds a driver for the blk-ctrl blocks found in the i.MX8M* line of
SoCs. The blk-ctrl is a top-level peripheral located in the various *MIX
power domains and interacts with the GPC power controller to provide the
peripherals in the power domain access to the NoC and ensures that those
peripherals are properly reset when their respective power domain is
brought back to life.

Software needs to do different things to make the bus handshake happen
after the GPC *MIX domain is powered up and before it is powered down.
As the requirements are quite different between the various blk-ctrls
there is a callback function provided to hook in the proper sequence.

The peripheral domains are quite uniform, they handle the soft clock
enables and resets in the blk-ctrl address space and sequencing with the
upstream GPC power domains.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
---
This commit includes the full code to drive the VPUMIX domain on the
i.MX8MM, as the skeleton driver would probably be harder to review
without the context provided by one blk-ctrl implementation. Other
blk-ctrl implementations will follow, based on this overall structure.

v4:
- fix commit message typos
- fix superfluous whitespace
- constify clk_names more
v5:
- add missing 'm' in the imx8mm_* structure names

2 files changed, 454 insertions, 0 deletions

diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
index 078dc918f4f3..8a707077914c 100644
--- a/drivers/soc/imx/Makefile
+++ b/drivers/soc/imx/Makefile
@@ -5,3 +5,4 @@ endif
 obj-$(CONFIG_HAVE_IMX_GPC) += gpc.o
 obj-$(CONFIG_IMX_GPCV2_PM_DOMAINS) += gpcv2.o
 obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o
+obj-$(CONFIG_SOC_IMX8M) += imx8m-blk-ctrl.o
diff --git a/drivers/soc/imx/imx8m-blk-ctrl.c b/drivers/soc/imx/imx8m-blk-ctrl.c
new file mode 100644
index 000000000000..f8db0ebd02c3
--- /dev/null
+++ b/drivers/soc/imx/imx8m-blk-ctrl.c
@@ -0,0 +1,453 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Copyright 2021 Pengutronix, Lucas Stach <kernel@pengutronix.de>
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/clk.h>
+
+#include <dt-bindings/power/imx8mm-power.h>
+
+#define BLK_SFT_RSTN	0x0
+#define BLK_CLK_EN	0x4
+
+struct imx8m_blk_ctrl_domain;
+
+struct imx8m_blk_ctrl {
+	struct device *dev;
+	struct notifier_block power_nb;
+	struct device *bus_power_dev;
+	struct regmap *regmap;
+	struct imx8m_blk_ctrl_domain *domains;
+	struct genpd_onecell_data onecell_data;
+};
+
+struct imx8m_blk_ctrl_domain_data {
+	const char *name;
+	const char * const *clk_names;
+	int num_clks;
+	const char *gpc_name;
+	u32 rst_mask;
+	u32 clk_mask;
+};
+
+#define DOMAIN_MAX_CLKS 3
+
+struct imx8m_blk_ctrl_domain {
+	struct generic_pm_domain genpd;
+	const struct imx8m_blk_ctrl_domain_data *data;
+	struct clk_bulk_data clks[DOMAIN_MAX_CLKS];
+	struct device *power_dev;
+	struct imx8m_blk_ctrl *bc;
+};
+
+struct imx8m_blk_ctrl_data {
+	int max_reg;
+	notifier_fn_t power_notifier_fn;
+	const struct imx8m_blk_ctrl_domain_data *domains;
+	int num_domains;
+};
+
+static inline struct imx8m_blk_ctrl_domain *
+to_imx8m_blk_ctrl_domain(struct generic_pm_domain *genpd)
+{
+	return container_of(genpd, struct imx8m_blk_ctrl_domain, genpd);
+}
+
+static int imx8m_blk_ctrl_power_on(struct generic_pm_domain *genpd)
+{
+	struct imx8m_blk_ctrl_domain *domain = to_imx8m_blk_ctrl_domain(genpd);
+	const struct imx8m_blk_ctrl_domain_data *data = domain->data;
+	struct imx8m_blk_ctrl *bc = domain->bc;
+	int ret;
+
+	/* make sure bus domain is awake */
+	ret = pm_runtime_get_sync(bc->bus_power_dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(bc->bus_power_dev);
+		dev_err(bc->dev, "failed to power up bus domain\n");
+		return ret;
+	}
+
+	/* put devices into reset */
+	regmap_clear_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
+
+	/* enable upstream and blk-ctrl clocks to allow reset to propagate */
+	ret = clk_bulk_prepare_enable(data->num_clks, domain->clks);
+	if (ret) {
+		dev_err(bc->dev, "failed to enable clocks\n");
+		goto bus_put;
+	}
+	regmap_set_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
+
+	/* power up upstream GPC domain */
+	ret = pm_runtime_get_sync(domain->power_dev);
+	if (ret < 0) {
+		dev_err(bc->dev, "failed to power up peripheral domain\n");
+		goto clk_disable;
+	}
+
+	/* wait for reset to propagate */
+	udelay(5);
+
+	/* release reset */
+	regmap_set_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
+
+	/* disable upstream clocks */
+	clk_bulk_disable_unprepare(data->num_clks, domain->clks);
+
+	return 0;
+
+clk_disable:
+	clk_bulk_disable_unprepare(data->num_clks, domain->clks);
+bus_put:
+	pm_runtime_put(bc->bus_power_dev);
+
+	return ret;
+}
+
+static int imx8m_blk_ctrl_power_off(struct generic_pm_domain *genpd)
+{
+	struct imx8m_blk_ctrl_domain *domain = to_imx8m_blk_ctrl_domain(genpd);
+	const struct imx8m_blk_ctrl_domain_data *data = domain->data;
+	struct imx8m_blk_ctrl *bc = domain->bc;
+
+	/* put devices into reset and disable clocks */
+	regmap_clear_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
+	regmap_clear_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
+
+	/* power down upstream GPC domain */
+	pm_runtime_put(domain->power_dev);
+
+	/* allow bus domain to suspend */
+	pm_runtime_put(bc->bus_power_dev);
+
+	return 0;
+}
+
+static struct generic_pm_domain *
+imx8m_blk_ctrl_xlate(struct of_phandle_args *args, void *data)
+{
+	struct genpd_onecell_data *onecell_data = data;
+	unsigned int index = args->args[0];
+
+	if (args->args_count != 1 ||
+	    index > onecell_data->num_domains)
+		return ERR_PTR(-EINVAL);
+
+	return onecell_data->domains[index];
+}
+
+static struct lock_class_key blk_ctrl_genpd_lock_class;
+
+static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
+{
+	const struct imx8m_blk_ctrl_data *bc_data;
+	struct device *dev = &pdev->dev;
+	struct imx8m_blk_ctrl *bc;
+	void __iomem *base;
+	int i, ret;
+
+	struct regmap_config regmap_config = {
+		.reg_bits	= 32,
+		.val_bits	= 32,
+		.reg_stride	= 4,
+	};
+
+	bc = devm_kzalloc(dev, sizeof(*bc), GFP_KERNEL);
+	if (!bc)
+		return -ENOMEM;
+
+	bc->dev = dev;
+
+	bc_data = of_device_get_match_data(dev);
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap_config.max_register = bc_data->max_reg;
+	bc->regmap = devm_regmap_init_mmio(dev, base, &regmap_config);
+	if (IS_ERR(bc->regmap))
+		return dev_err_probe(dev, PTR_ERR(bc->regmap),
+				     "failed to init regmap\n");
+
+	bc->domains = devm_kcalloc(dev, bc_data->num_domains,
+				   sizeof(struct imx8m_blk_ctrl_domain),
+				   GFP_KERNEL);
+	if (!bc->domains)
+		return -ENOMEM;
+
+	bc->onecell_data.num_domains = bc_data->num_domains;
+	bc->onecell_data.xlate = imx8m_blk_ctrl_xlate;
+	bc->onecell_data.domains =
+		devm_kcalloc(dev, bc_data->num_domains,
+			     sizeof(struct generic_pm_domain *), GFP_KERNEL);
+	if (!bc->onecell_data.domains)
+		return -ENOMEM;
+
+	bc->bus_power_dev = genpd_dev_pm_attach_by_name(dev, "bus");
+	if (IS_ERR(bc->bus_power_dev))
+		return dev_err_probe(dev, PTR_ERR(bc->bus_power_dev),
+				     "failed to attach power domain\n");
+
+	for (i = 0; i < bc_data->num_domains; i++) {
+		const struct imx8m_blk_ctrl_domain_data *data = &bc_data->domains[i];
+		struct imx8m_blk_ctrl_domain *domain = &bc->domains[i];
+		int j;
+
+		domain->data = data;
+
+		for (j = 0; j < data->num_clks; j++)
+			domain->clks[j].id = data->clk_names[j];
+
+		ret = devm_clk_bulk_get(dev, data->num_clks, domain->clks);
+		if (ret) {
+			dev_err_probe(dev, ret, "failed to get clock\n");
+			goto cleanup_pds;
+		}
+
+		domain->power_dev =
+			dev_pm_domain_attach_by_name(dev, data->gpc_name);
+		if (IS_ERR(domain->power_dev)) {
+			dev_err_probe(dev, PTR_ERR(domain->power_dev),
+				      "failed to attach power domain\n");
+			ret = PTR_ERR(domain->power_dev);
+			goto cleanup_pds;
+		}
+
+		domain->genpd.name = data->name;
+		domain->genpd.power_on = imx8m_blk_ctrl_power_on;
+		domain->genpd.power_off = imx8m_blk_ctrl_power_off;
+		domain->bc = bc;
+
+		ret = pm_genpd_init(&domain->genpd, NULL, true);
+		if (ret) {
+			dev_err_probe(dev, ret, "failed to init power domain\n");
+			dev_pm_domain_detach(domain->power_dev, true);
+			goto cleanup_pds;
+		}
+
+		/*
+		 * We use runtime PM to trigger power on/off of the upstream GPC
+		 * domain, as a strict hierarchical parent/child power domain
+		 * setup doesn't allow us to meet the sequencing requirements.
+		 * This means we have nested locking of genpd locks, without the
+		 * nesting being visible at the genpd level, so we need a
+		 * separate lock class to make lockdep aware of the fact that
+		 * this are separate domain locks that can be nested without a
+		 * self-deadlock.
+		 */
+		lockdep_set_class(&domain->genpd.mlock,
+				  &blk_ctrl_genpd_lock_class);
+
+		bc->onecell_data.domains[i] = &domain->genpd;
+	}
+
+	ret = of_genpd_add_provider_onecell(dev->of_node, &bc->onecell_data);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to add power domain provider\n");
+		goto cleanup_pds;
+	}
+
+	bc->power_nb.notifier_call = bc_data->power_notifier_fn;
+	ret = dev_pm_genpd_add_notifier(bc->bus_power_dev, &bc->power_nb);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to add power notifier\n");
+		goto cleanup_provider;
+	}
+
+	dev_set_drvdata(dev, bc);
+
+	return 0;
+
+cleanup_provider:
+	of_genpd_del_provider(dev->of_node);
+cleanup_pds:
+	for (i--; i >= 0; i--) {
+		pm_genpd_remove(&bc->domains[i].genpd);
+		dev_pm_domain_detach(bc->domains[i].power_dev, true);
+	}
+
+	dev_pm_domain_detach(bc->bus_power_dev, true);
+
+	return ret;
+}
+
+static int imx8m_blk_ctrl_remove(struct platform_device *pdev)
+{
+	struct imx8m_blk_ctrl *bc = dev_get_drvdata(&pdev->dev);
+	int i;
+
+	of_genpd_del_provider(pdev->dev.of_node);
+
+	for (i = 0; bc->onecell_data.num_domains; i++) {
+		struct imx8m_blk_ctrl_domain *domain = &bc->domains[i];
+
+		pm_genpd_remove(&domain->genpd);
+		dev_pm_domain_detach(domain->power_dev, true);
+	}
+
+	dev_pm_genpd_remove_notifier(bc->bus_power_dev);
+
+	dev_pm_domain_detach(bc->bus_power_dev, true);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int imx8m_blk_ctrl_suspend(struct device *dev)
+{
+	struct imx8m_blk_ctrl *bc = dev_get_drvdata(dev);
+	int ret, i;
+
+	/*
+	 * This may look strange, but is done so the generic PM_SLEEP code
+	 * can power down our domains and more importantly power them up again
+	 * after resume, without tripping over our usage of runtime PM to
+	 * control the upstream GPC domains. Things happen in the right order
+	 * in the system suspend/resume paths due to the device parent/child
+	 * hierarchy.
+	 */
+	ret = pm_runtime_get_sync(bc->bus_power_dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(bc->bus_power_dev);
+		return ret;
+	}
+
+	for (i = 0; i < bc->onecell_data.num_domains; i++) {
+		struct imx8m_blk_ctrl_domain *domain = &bc->domains[i];
+
+		ret = pm_runtime_get_sync(domain->power_dev);
+		if (ret < 0) {
+			pm_runtime_put_noidle(domain->power_dev);
+			goto out_fail;
+		}
+	}
+
+	return 0;
+
+out_fail:
+	for (i--; i >= 0; i--)
+		pm_runtime_put(bc->domains[i].power_dev);
+
+	pm_runtime_put(bc->bus_power_dev);
+
+	return ret;
+}
+
+static int imx8m_blk_ctrl_resume(struct device *dev)
+{
+	struct imx8m_blk_ctrl *bc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < bc->onecell_data.num_domains; i++)
+		pm_runtime_put(bc->domains[i].power_dev);
+
+	pm_runtime_put(bc->bus_power_dev);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops imx8m_blk_ctrl_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(imx8m_blk_ctrl_suspend, imx8m_blk_ctrl_resume)
+};
+
+static int imx8mm_vpu_power_notifier(struct notifier_block *nb,
+				     unsigned long action, void *data)
+{
+	struct imx8m_blk_ctrl *bc = container_of(nb, struct imx8m_blk_ctrl,
+						 power_nb);
+
+	if (action != GENPD_NOTIFY_ON && action != GENPD_NOTIFY_PRE_OFF)
+		return NOTIFY_OK;
+
+	/*
+	 * The ADB in the VPUMIX domain has no separate reset and clock
+	 * enable bits, but is ungated together with the VPU clocks. To
+	 * allow the handshake with the GPC to progress we put the VPUs
+	 * in reset and ungate the clocks.
+	 */
+	regmap_clear_bits(bc->regmap, BLK_SFT_RSTN, BIT(0) | BIT(1) | BIT(2));
+	regmap_set_bits(bc->regmap, BLK_CLK_EN, BIT(0) | BIT(1) | BIT(2));
+
+	if (action == GENPD_NOTIFY_ON) {
+		/*
+		 * On power up we have no software backchannel to the GPC to
+		 * wait for the ADB handshake to happen, so we just delay for a
+		 * bit. On power down the GPC driver waits for the handshake.
+		 */
+		udelay(5);
+
+		/* set "fuse" bits to enable the VPUs */
+		regmap_set_bits(bc->regmap, 0x8, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0xc, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0x10, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0x14, 0xffffffff);
+	}
+
+	return NOTIFY_OK;
+}
+
+static const struct imx8m_blk_ctrl_domain_data imx8mm_vpu_blk_ctl_domain_data[] = {
+	[IMX8MM_VPUBLK_PD_G1] = {
+		.name = "vpublk-g1",
+		.clk_names = (const char *[]){ "g1", },
+		.num_clks = 1,
+		.gpc_name = "g1",
+		.rst_mask = BIT(1),
+		.clk_mask = BIT(1),
+	},
+	[IMX8MM_VPUBLK_PD_G2] = {
+		.name = "vpublk-g2",
+		.clk_names = (const char *[]){ "g2", },
+		.num_clks = 1,
+		.gpc_name = "g2",
+		.rst_mask = BIT(0),
+		.clk_mask = BIT(0),
+	},
+	[IMX8MM_VPUBLK_PD_H1] = {
+		.name = "vpublk-h1",
+		.clk_names = (const char *[]){ "h1", },
+		.num_clks = 1,
+		.gpc_name = "h1",
+		.rst_mask = BIT(2),
+		.clk_mask = BIT(2),
+	},
+};
+
+static const struct imx8m_blk_ctrl_data imx8mm_vpu_blk_ctl_dev_data = {
+	.max_reg = 0x18,
+	.power_notifier_fn = imx8mm_vpu_power_notifier,
+	.domains = imx8mm_vpu_blk_ctl_domain_data,
+	.num_domains = ARRAY_SIZE(imx8mm_vpu_blk_ctl_domain_data),
+};
+
+static const struct of_device_id imx8m_blk_ctrl_of_match[] = {
+	{
+		.compatible = "fsl,imx8mm-vpu-blk-ctrl",
+		.data = &imx8mm_vpu_blk_ctl_dev_data
+	}, {
+		/* Sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, imx8m_blk_ctrl_of_match);
+
+static struct platform_driver imx8m_blk_ctrl_driver = {
+	.probe = imx8m_blk_ctrl_probe,
+	.remove = imx8m_blk_ctrl_remove,
+	.driver = {
+		.name = "imx8m-blk-ctrl",
+		.pm = &imx8m_blk_ctrl_pm_ops,
+		.of_match_table = imx8m_blk_ctrl_of_match,
+	},
+};
+module_platform_driver(imx8m_blk_ctrl_driver);