[RFC 9/9] PCI/pwrctl: add a PCI power control driver for power sequenced devices

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Add a PCI power control driver that's capable of correctly powering up
devices using the power sequencing subsystem. For now we support the
ath11k module on QCA6390.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/pci/pwrctl/Kconfig             |  9 +++
 drivers/pci/pwrctl/Makefile            |  1 +
 drivers/pci/pwrctl/pci-pwrctl-pwrseq.c | 83 ++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 drivers/pci/pwrctl/pci-pwrctl-pwrseq.c

diff --git a/drivers/pci/pwrctl/Kconfig b/drivers/pci/pwrctl/Kconfig
index e2dc5e5d2af1..bca72dc08e79 100644
--- a/drivers/pci/pwrctl/Kconfig
+++ b/drivers/pci/pwrctl/Kconfig
@@ -5,4 +5,13 @@ menu "PCI Power control drivers"
 config PCI_PWRCTL
 	bool
 
+config PCI_PWRCTL_PWRSEQ
+	tristate "PCI Power Control driver using the Power Sequencing subsystem"
+	select POWER_SEQUENCING
+	select PCI_PWRCTL
+	default m if (ATH11K_PCI && ARCH_QCOM)
+	help
+	  Enable support for the PCI power control driver for device
+	  drivers using the Power Sequencing subsystem.
+
 endmenu
diff --git a/drivers/pci/pwrctl/Makefile b/drivers/pci/pwrctl/Makefile
index 4381cfbf3f21..919c0f704ee9 100644
--- a/drivers/pci/pwrctl/Makefile
+++ b/drivers/pci/pwrctl/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_PCI_PWRCTL)		+= core.o
+obj-$(CONFIG_PCI_PWRCTL_PWRSEQ)		+= pci-pwrctl-pwrseq.o
diff --git a/drivers/pci/pwrctl/pci-pwrctl-pwrseq.c b/drivers/pci/pwrctl/pci-pwrctl-pwrseq.c
new file mode 100644
index 000000000000..510598c4edc4
--- /dev/null
+++ b/drivers/pci/pwrctl/pci-pwrctl-pwrseq.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023-2024 Linaro Ltd.
+ */
+
+#include <linux/device.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pci-pwrctl.h>
+#include <linux/platform_device.h>
+#include <linux/pwrseq/consumer.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+struct pci_pwrctl_pwrseq_data {
+	struct pci_pwrctl ctx;
+	struct pwrseq_desc *pwrseq;
+};
+
+static void devm_pci_pwrctl_pwrseq_power_off(void *data)
+{
+	struct pwrseq_desc *pwrseq = data;
+
+	pwrseq_power_off(pwrseq);
+}
+
+static int pci_pwrctl_pwrseq_probe(struct platform_device *pdev)
+{
+	struct pci_pwrctl_pwrseq_data *data;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->pwrseq = devm_pwrseq_get(dev);
+	if (IS_ERR(data->pwrseq))
+		return dev_err_probe(dev, PTR_ERR(data->pwrseq),
+				     "Failed to get the power sequencer\n");
+
+	ret = pwrseq_power_on(data->pwrseq);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to power-on the device\n");
+
+	ret = devm_add_action_or_reset(dev, devm_pci_pwrctl_pwrseq_power_off,
+				       data->pwrseq);
+	if (ret)
+		return ret;
+
+	data->ctx.dev = dev;
+
+	ret = devm_pci_pwrctl_device_enable(dev, &data->ctx);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to register the pwrctl wrapper\n");
+
+	return 0;
+}
+
+static const struct of_device_id pci_pwrctl_pwrseq_of_match[] = {
+	{
+		/* ATH11K in QCA6390 package. */
+		.compatible = "pci17cb,1101",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pci_pwrctl_pwrseq_of_match);
+
+static struct platform_driver pci_pwrctl_pwrseq_driver = {
+	.driver = {
+		.name = "pci-pwrctl-pwrseq",
+		.of_match_table = pci_pwrctl_pwrseq_of_match,
+	},
+	.probe = pci_pwrctl_pwrseq_probe,
+};
+module_platform_driver(pci_pwrctl_pwrseq_driver);
+
+MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
+MODULE_DESCRIPTION("Generic PCI Power Control module for power sequenced devices");
+MODULE_LICENSE("GPL");
-- 
2.40.1