[PATCH RFC] WIP: mfd: add support for Qualcomm RPM

[Josh Cartwright <joshc@codeaurora.org>]

The Resource Power Manager (RPM) is responsible managing SoC-wide
resources (clocks, regulators, etc) on MSM and other Qualcomm SoCs.
This driver provides an implementation of the message-RAM-based
communication protocol.

Note, this is a rewrite of the driver as it exists in the downstream
tree[1], making a few simplifying assumptions to clean it up, and adding
device tree support.

[1]: https://www.codeaurora.org/cgit/quic/la/kernel/msm/tree/arch/arm/mach-msm/rpm.c?h=msm-3.4

Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
---
This patch is intended to act as a starting point for discussions on how we
should proceed going forward supporting RPM.  In particular, figuring out how
to model RPM and it's controlled resources in device tree.

I've chosen a path where a subnode logically separates the RPM resources; it's
intended each set of resources will be controlled by a single driver.  For
example, an RPM-controlled regulator might consume two RPM_TYPE_REQ resources
described in 'reg'.

Effectively, this pushes the "generic resource ID" -> "SoC-specific resource
ID" mapping out of the large data tables that exist in msm-3.4 into the device
tree.  An alternative approach would be to still maintain the SoC-specific
tables, and have each node matched to it's resources using a unique compatible
string.

Any comments appreciated!

Thanks,
  Josh
 Documentation/devicetree/bindings/mfd/qcom,rpm.txt |  68 +++++
 drivers/mfd/Kconfig                                |   9 +
 drivers/mfd/Makefile                               |   1 +
 drivers/mfd/qcom-rpm.c                             | 314 +++++++++++++++++++++
 include/linux/mfd/qcom_rpm.h                       |  64 +++++
 5 files changed, 456 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/qcom,rpm.txt
 create mode 100644 drivers/mfd/qcom-rpm.c
 create mode 100644 include/linux/mfd/qcom_rpm.h

diff --git a/Documentation/devicetree/bindings/mfd/qcom,rpm.txt b/Documentation/devicetree/bindings/mfd/qcom,rpm.txt
new file mode 100644
index 0000000..617018f
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/qcom,rpm.txt
@@ -0,0 +1,68 @@
+Qualcomm Resource Power Manager (RPM)
+
+This driver is used to interface with Resource Power Manager (RPM).  The RPM is
+responsible managing SoC-wide resources (clocks, regulators, etc) on MSM and
+other Qualcomm chipsets.
+
+Required properties:
+
+- compatible: must be one of:
+	"qcom,rpm-apq8064"
+	"qcom,rpm-ipq8064"
+
+- reg: must contain two register specifiers, in the following order:
+	specifier 0: RPM Message RAM
+	specifier 1: IPC register
+
+- reg-names: must contain the following, in order:
+	"msg_ram"
+	"ipc"
+
+- interrupts: must contain the following three interrupt specifiers, in order:
+	specifier 0: RPM Acknowledgement Interrupt
+	specifier 1: Error Interrupt
+	specifier 2: Wakeup interrupt
+
+- interrupt-names: must contain the following, in order:
+	"ack"
+	"err"
+	"wakeup"
+
+- ipc-bit: bit written to the IPC register to notify RPM of a pending request
+
+- #address-cells: must be 3
+	cell 0: offset in ACK and REQ register spaces corresponding to the register
+	cell 1: type field, one of RPM_TYPE_REQ (0) or RPM_TYPE_STATUS (1)
+	cell 2: indicates the selector bit to set when writing this register,
+		this cell is ignored (and should be set to zero) when type is
+		RPM_TYPE_STATUS
+
+Example:
+
+	#include <dt-bindings/mfd/qcom_rpm.h>
+
+	rpm@108000 {
+		compatible = "qcom,rpm-ipq8064";
+		reg = <0x00108000 0x1000>,
+		      <0x02011008 0x4>;
+		reg-names = "msg_ram",
+			    "ipc";
+		interrupts = <GIC_SPI 19 0>,
+			     <GIC_SPI 21 0>,
+			     <GIC_SPI 22 0>;
+		interrupt-names = "ack",
+				  "err",
+				  "wakeup";
+		ipc-bit = <2>;
+
+		#address-cells = <3>;
+		#size-cells = <0>;
+
+		subnode {
+			compatible = "...";
+			reg = <464 RPM_TYPE_REQ 30>,
+			      <468 RPM_TYPE_REQ 30>,
+			      <118 RPM_TYPE_STATUS 0>;
+		};
+	};
+
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 49bb445..b387ba9 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -497,6 +497,15 @@ config MFD_PM8XXX_IRQ
 	  This is required to use certain other PM 8xxx features, such as GPIO
 	  and MPP.
 
+config MFD_QCOM_RPM
+	tristate "Qualcomm Resource Power Manager (RPM) driver"
+	depends on (ARCH_QCOM || COMPILE_TEST)
+	help
+	  The Resource Power Manager (RPM) is responsible managing SoC-wide
+	  resources (clocks, regulators, etc) on MSM and other Qualcomm SoCs.
+	  This driver provides an implementation of the message-RAM-based
+	  communication protocol.
+
 config MFD_RDC321X
 	tristate "RDC R-321x southbridge"
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 5aea5ef..a51fe46 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -151,6 +151,7 @@ obj-$(CONFIG_MFD_CS5535)	+= cs5535-mfd.o
 obj-$(CONFIG_MFD_OMAP_USB_HOST)	+= omap-usb-host.o omap-usb-tll.o
 obj-$(CONFIG_MFD_PM8921_CORE) 	+= pm8921-core.o ssbi.o
 obj-$(CONFIG_MFD_PM8XXX_IRQ) 	+= pm8xxx-irq.o
+obj-$(CONFIG_MFD_QCOM_RPM)	+= qcom-rpm.o
 obj-$(CONFIG_TPS65911_COMPARATOR)	+= tps65911-comparator.o
 obj-$(CONFIG_MFD_TPS65090)	+= tps65090.o
 obj-$(CONFIG_MFD_AAT2870_CORE)	+= aat2870-core.o
diff --git a/drivers/mfd/qcom-rpm.c b/drivers/mfd/qcom-rpm.c
new file mode 100644
index 0000000..ff33bc6
--- /dev/null
+++ b/drivers/mfd/qcom-rpm.c
@@ -0,0 +1,314 @@
+/* Copyright (c) 2010-2012,2014 The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/qcom_rpm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#include <dt-bindings/mfd/qcom-rpm.h>
+
+#define RPM_SUPPORTED_VERS_MAJOR	3
+
+#define RPM_STATUS_VERSION_MAJOR	0
+
+#define RPM_CONTROL_VERSION_MAJOR	0x00
+#define RPM_CONTROL_VERSION_MINOR	0x04
+#define RPM_CONTROL_VERSION_BUILD	0x08
+#define RPM_CONTROL_REQ_CTX		0x0C
+#define RPM_CONTROL_REQ_SEL		0x2C
+#define RPM_CONTROL_ACK_CTX		0x3C
+#define RPM_CONTROL_ACK_SEL		0x5C
+
+struct qcom_rpm {
+	struct device *dev;
+	void __iomem *status;
+	void __iomem *ctrl;
+	void __iomem *req;
+	void __iomem *ack;
+	void __iomem *ipc_reg;
+	u32 ipc_val;
+	u32 *ctx_ack;
+	u32 (*sel_masks_ack)[5];
+	struct qcom_rpm_req *pending_req;
+	size_t num_req;
+	struct completion done;
+	struct mutex lock;
+};
+
+static void qcom_rpm_kick(struct qcom_rpm *rpm)
+{
+	writel(rpm->ipc_val, rpm->ipc_reg);
+}
+
+int qcom_rpm_write_ctx(struct qcom_rpm *rpm, enum qcom_rpm_context_mask ctx,
+		       const struct qcom_rpm_req *req, u32 *data, size_t len)
+{
+	u32 __iomem *req_sel_reg = rpm->ctrl + RPM_CONTROL_REQ_SEL;
+	u32 sel_masks[5] = { }, sel_masks_ack[5];
+	u32 ctx_ack;
+	size_t i;
+
+	for (i = 0; i < len; i++)
+		sel_masks[req->sel_reg] |= req->sel_mask;
+
+	mutex_lock(&rpm->lock);
+
+	rpm->ctx_ack = &ctx_ack;
+	rpm->sel_masks_ack = &sel_masks_ack;
+
+	for (i = 0; i < len; i++)
+		writel_relaxed(data[i], rpm->req + req[i].offset);
+
+	for (i = 0; i < ARRAY_SIZE(sel_masks); i++)
+		writel_relaxed(sel_masks[i], &req_sel_reg[i]);
+
+	writel_relaxed(ctx, rpm->ctrl + RPM_CONTROL_REQ_CTX);
+
+	qcom_rpm_kick(rpm);
+
+	wait_for_completion(&rpm->done);
+	reinit_completion(&rpm->done);
+
+	for (i = 0; i < rpm->num_req; i++)
+		data[i] = readl_relaxed(rpm->ack + rpm->pending_req[i].offset);
+
+	mutex_unlock(&rpm->lock);
+
+	if (ctx_ack & QCOM_RPM_CTX_REJECTED)
+		return -ENOSPC;
+
+	ctx_ack &= ~QCOM_RPM_CTX_REJECTED;
+	if (WARN_ON(ctx_ack != ctx)) {
+		dev_err(rpm->dev, "received bad context ack.\n");
+		return -EFAULT;
+	}
+
+	if (WARN_ON(memcmp(sel_masks, sel_masks_ack, sizeof(sel_masks)))) {
+		dev_err(rpm->dev,
+			"requested writes failed to be acknowledged.\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(qcom_rpm_write_ctx);
+
+static irqreturn_t qcom_rpm_ack_irq(int irq, void *devid)
+{
+	struct qcom_rpm *rpm = devid;
+	u32 __iomem *ack_sel_reg = rpm->ctrl + RPM_CONTROL_ACK_SEL;
+	unsigned int i;
+
+	*rpm->ctx_ack = readl_relaxed(rpm->ctrl + RPM_CONTROL_ACK_CTX);
+
+	for (i = 0; i < ARRAY_SIZE(*rpm->sel_masks_ack); i++) {
+		*rpm->sel_masks_ack[i] = readl_relaxed(&ack_sel_reg[i]);
+		writel_relaxed(0, &ack_sel_reg[i]);
+	}
+
+	writel_relaxed(0, rpm->ctrl + RPM_CONTROL_ACK_CTX);
+
+	/* Ignore notifications for now */
+	if (*rpm->ctx_ack & QCOM_RPM_CTX_NOTIFICATION)
+		return IRQ_HANDLED;
+
+	complete(&rpm->done);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t qcom_rpm_err_irq(int irq, void *devid)
+{
+	struct qcom_rpm *rpm = devid;
+
+	WARN(1, "RPM triggered fatal error. RPM communication unreliable.");
+	writel_relaxed(1, rpm->ipc_reg);
+
+	return IRQ_HANDLED;
+}
+
+static const __be32 *qcom_decode_reg_type(struct platform_device *pdev,
+					  unsigned int which, unsigned int type)
+{
+	const struct device_node *np = pdev->dev.of_node;
+	const __be32 *cell;
+	int sz;
+
+	cell = of_get_property(np, "reg", &sz);
+	if (!cell)
+		return ERR_PTR(-EINVAL);
+
+	sz /= 3 * sizeof(u32);
+
+	for (; sz--; cell += 3) {
+
+		if (be32_to_cpup(&cell[1]) != type)
+			continue;
+
+		if (!which--)
+			return cell;
+
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+int qcom_rpm_get_req(struct platform_device *pdev, unsigned int which,
+		     struct qcom_rpm_req *req)
+{
+	const __be32 *cell;
+	u32 sel_bit;
+
+	cell = qcom_decode_reg_type(pdev, which, RPM_TYPE_REQ);
+	if (IS_ERR(cell))
+		return PTR_ERR(cell);
+
+	req->offset = be32_to_cpup(&cell[0]);
+
+	sel_bit = be32_to_cpup(&cell[2]);
+
+	req->sel_reg  = sel_bit / 32;
+	req->sel_mask = BIT(sel_bit % 32);
+	return 0;
+}
+EXPORT_SYMBOL(qcom_rpm_get_req);
+
+const void __iomem *qcom_rpm_get_status(struct platform_device *pdev,
+					unsigned int which)
+{
+	struct qcom_rpm *rpm = qcom_rpm_get(pdev);
+	const __be32 *cell;
+
+	cell = qcom_decode_reg_type(pdev, which, RPM_TYPE_STATUS);
+	if (IS_ERR(cell))
+		return (const void __iomem *) cell;
+
+	return rpm->status + be32_to_cpup(&cell[0]);
+}
+EXPORT_SYMBOL(qcom_rpm_get_status);
+
+static int qcom_rpm_check_version(struct qcom_rpm *rpm)
+{
+	u32 vers_major;
+
+	vers_major = readl_relaxed(rpm->status + RPM_STATUS_VERSION_MAJOR);
+
+	if (vers_major != RPM_SUPPORTED_VERS_MAJOR) {
+		dev_err(rpm->dev, "RPM driver does not support firmware with major version %d\n",
+			vers_major);
+		return -EINVAL;
+	}
+
+	writel_relaxed(vers_major, rpm->ctrl + RPM_CONTROL_VERSION_MAJOR);
+	writel_relaxed(0, rpm->ctrl + RPM_CONTROL_VERSION_MINOR);
+	writel_relaxed(0, rpm->ctrl + RPM_CONTROL_VERSION_BUILD);
+	return 0;
+}
+
+static int qcom_rpm_probe(struct platform_device *pdev)
+{
+	struct qcom_rpm *rpm;
+	struct resource *res;
+	int err, irq;
+	u32 bit;
+
+	rpm = devm_kzalloc(&pdev->dev, sizeof(*rpm), GFP_KERNEL);
+	if (!rpm)
+		return -ENOMEM;
+
+	rpm->dev = &pdev->dev;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "msg_ram");
+	rpm->status = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rpm->status))
+		return PTR_ERR(rpm->status);
+
+	rpm->ctrl = rpm->status + 0x400;
+	rpm->req  = rpm->status + 0x600;
+	rpm->ack  = rpm->status + 0xA00;
+
+	err = qcom_rpm_check_version(rpm);
+	if (err)
+		return err;
+
+	init_completion(&rpm->done);
+	mutex_init(&rpm->lock);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ipc");
+	rpm->ipc_reg = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rpm->ipc_reg))
+		return PTR_ERR(rpm->ipc_reg);
+
+	err = of_property_read_u32(pdev->dev.of_node, "ipc-bit", &bit);
+	if (err) {
+		dev_err(&pdev->dev, "ipc-bit property unspecified.\n");
+		return -EINVAL;
+	}
+
+	if (bit > 31) {
+		dev_err(&pdev->dev, "invalid ipc-bit specified.\n");
+		return -EINVAL;
+	}
+
+	rpm->ipc_val = BIT(bit);
+
+	irq = platform_get_irq_byname(pdev, "ack");
+	if (irq < 0) {
+		dev_err(&pdev->dev, "invalid ack interrupt specified.\n");
+		return irq;
+	}
+
+	err = devm_request_irq(&pdev->dev, irq, qcom_rpm_ack_irq,
+			       IRQF_TRIGGER_RISING, "rpm_ack", rpm);
+	if (err) {
+		dev_err(&pdev->dev, "unable to request ack interrupt\n");
+		return err;
+	}
+
+	irq = platform_get_irq_byname(pdev, "err");
+	if (irq < 0) {
+		dev_err(&pdev->dev, "invalid err interrupt specified.\n");
+		return irq;
+	}
+
+	err = devm_request_irq(&pdev->dev, irq, qcom_rpm_err_irq,
+			       IRQF_TRIGGER_RISING, "rpm_err", rpm);
+	if (err) {
+		dev_err(&pdev->dev, "unable to request err interrupt\n");
+		return err;
+	}
+
+	platform_set_drvdata(pdev, rpm);
+
+	return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+}
+
+static const struct of_device_id qcom_rpm_of_match[] = {
+	{ .compatible = "qcom,rpm-apq8064", },
+	{ .compatible = "qcom,rpm-ipq8064", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qcom_rpm_of_match);
+
+static struct platform_driver msm_rpm_platform_driver = {
+	.probe			= qcom_rpm_probe,
+	.driver = {
+		.name		= "qcom_rpm",
+		.of_match_table	= qcom_rpm_of_match,
+	},
+};
+module_platform_driver(msm_rpm_platform_driver);
diff --git a/include/linux/mfd/qcom_rpm.h b/include/linux/mfd/qcom_rpm.h
new file mode 100644
index 0000000..1f585bf
--- /dev/null
+++ b/include/linux/mfd/qcom_rpm.h
@@ -0,0 +1,64 @@
+/* Copyright (c) 2014 The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#ifndef QCOM_RPM_H
+#define QCOM_RPM_H
+
+#include <linux/platform_device.h>
+
+struct qcom_rpm;
+
+static inline struct qcom_rpm *qcom_rpm_get(struct platform_device *pdev)
+{
+	struct platform_device *parent;
+
+	parent = to_platform_device(pdev->dev.parent);
+
+	return platform_get_drvdata(parent);
+}
+
+struct qcom_rpm_req {
+	unsigned int offset;
+	unsigned int sel_reg;
+	u32 sel_mask;
+};
+
+enum qcom_rpm_context_mask {
+	QCOM_RPM_CTX_SET_ACTIVE		= BIT(0),
+	QCOM_RPM_CTX_SET_SLEEP		= BIT(1),
+	QCOM_RPM_CTX_NOTIFICATION	= BIT(30),
+	QCOM_RPM_CTX_REJECTED		= BIT(31),
+};
+
+int qcom_rpm_write_ctx(struct qcom_rpm *rpm, enum qcom_rpm_context_mask ctx,
+		       const struct qcom_rpm_req *req, u32 *data, size_t len);
+
+static inline int qcom_rpm_req_write(struct qcom_rpm *rpm,
+				     const struct qcom_rpm_req *req, u32 data)
+{
+	return qcom_rpm_write_ctx(rpm, QCOM_RPM_CTX_SET_ACTIVE, req, &data, 1);
+}
+
+static inline int qcom_rpm_req_write_sleep(struct qcom_rpm *rpm,
+					   const struct qcom_rpm_req *req,
+					   u32 data)
+{
+	return qcom_rpm_write_ctx(rpm, QCOM_RPM_CTX_SET_SLEEP, req, &data, 1);
+}
+
+int qcom_rpm_get_req(struct platform_device *pdev, unsigned int which,
+		     struct qcom_rpm_req *req);
+
+const void __iomem *qcom_rpm_get_status(struct platform_device *pdev,
+					unsigned int which);
+
+#endif /* QCOM_RPM_H */
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation