Date:   Wed,  4 Dec 2019 15:29:15 -0800
From:   Jolly Shah <jolly.shah@...inx.com>
To:     ard.biesheuvel@...aro.org, mingo@...nel.org,
        gregkh@...uxfoundation.org, matt@...eblueprint.co.uk,
        sudeep.holla@....com, hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, michal.simek@...inx.com
Cc:     rajanv@...inx.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Rajan Vaja <rajan.vaja@...inx.com>,
        Jolly Shah <jolly.shah@...inx.com>
Subject: [PATCH 1/5] firmware: xilinx: Adds new eemi call for reg access

From: Rajan Vaja <rajan.vaja@...inx.com>

This patch adds new EEMI call which is used for CSU/PMU register
access from linux.

Signed-off-by: Michal Simek <michal.simek@...inx.com>
Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
Signed-off-by: Jolly Shah <jolly.shah@...inx.com>
---
 drivers/firmware/xilinx/zynqmp.c     | 183 +++++++++++++++++++++++++++++++++++
 include/linux/firmware/xlnx-zynqmp.h |   9 ++
 2 files changed, 192 insertions(+)

diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
index fd3d837..56431ad 100644
--- a/drivers/firmware/xilinx/zynqmp.c
+++ b/drivers/firmware/xilinx/zynqmp.c
@@ -24,6 +24,8 @@
 #include <linux/firmware/xlnx-zynqmp.h>
 #include "zynqmp-debug.h"
 
+static unsigned long register_address;
+
 static const struct zynqmp_eemi_ops *eemi_ops_tbl;
 
 static const struct mfd_cell firmware_devs[] = {
@@ -664,6 +666,26 @@ static int zynqmp_pm_set_requirement(const u32 node, const u32 capabilities,
 				   qos, ack, NULL);
 }
 
+/**
+ * zynqmp_pm_config_reg_access - PM Config API for Config register access
+ * @register_access_id:	ID of the requested REGISTER_ACCESS
+ * @address:		Address of the register to be accessed
+ * @mask:		Mask to be written to the register
+ * @value:		Value to be written to the register
+ * @out:		Returned output value
+ *
+ * This function calls REGISTER_ACCESS to configure CSU/PMU registers.
+ *
+ * Return:	Returns status, either success or error+reason
+ */
+
+static int zynqmp_pm_config_reg_access(u32 register_access_id, u32 address,
+				       u32 mask, u32 value, u32 *out)
+{
+	return zynqmp_pm_invoke_fn(PM_REGISTER_ACCESS, register_access_id,
+				   address, mask, value, out);
+}
+
 static const struct zynqmp_eemi_ops eemi_ops = {
 	.get_api_version = zynqmp_pm_get_api_version,
 	.get_chipid = zynqmp_pm_get_chipid,
@@ -687,6 +709,7 @@ static const struct zynqmp_eemi_ops eemi_ops = {
 	.set_requirement = zynqmp_pm_set_requirement,
 	.fpga_load = zynqmp_pm_fpga_load,
 	.fpga_get_status = zynqmp_pm_fpga_get_status,
+	.register_access = zynqmp_pm_config_reg_access,
 };
 
 /**
@@ -704,6 +727,160 @@ const struct zynqmp_eemi_ops *zynqmp_pm_get_eemi_ops(void)
 }
 EXPORT_SYMBOL_GPL(zynqmp_pm_get_eemi_ops);
 
+/**
+ * config_reg_store - Write config_reg sysfs attribute
+ * @kobj:	Kobject structure
+ * @attr:	Kobject attribute structure
+ * @buf:	User entered health_status attribute string
+ * @count:	Buffer size
+ *
+ * User-space interface for setting the config register.
+ *
+ * To write any CSU/PMU register
+ * echo <address> <mask> <values> > /sys/firmware/zynqmp/config_reg
+ * Usage:
+ * echo 0x345AB234 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/config_reg
+ *
+ * To Read any CSU/PMU register, write address to the variable like below
+ * echo <address> > /sys/firmware/zynqmp/config_reg
+ *
+ * Return:	count argument if request succeeds, the corresponding error
+ *		code otherwise
+ */
+static ssize_t config_reg_store(struct kobject *kobj,
+				struct kobj_attribute *attr,
+				const char *buf, size_t count)
+{
+	char *kern_buff, *inbuf, *tok;
+	unsigned long address, value, mask;
+	int ret;
+
+	kern_buff = kzalloc(count, GFP_KERNEL);
+	if (!kern_buff)
+		return -ENOMEM;
+
+	ret = strlcpy(kern_buff, buf, count);
+	if (ret < 0) {
+		ret = -EFAULT;
+		goto err;
+	}
+
+	inbuf = kern_buff;
+
+	/* Read the addess */
+	tok = strsep(&inbuf, " ");
+	if (!tok) {
+		ret = -EFAULT;
+		goto err;
+	}
+	ret = kstrtol(tok, 16, &address);
+	if (ret) {
+		ret = -EFAULT;
+		goto err;
+	}
+	/* Read the write value */
+	tok = strsep(&inbuf, " ");
+	/*
+	 * If parameter provided is only address, then its a read operation.
+	 * Store the address in a global variable and retrieve whenever
+	 * required.
+	 */
+	if (!tok) {
+		register_address = address;
+		goto err;
+	}
+	register_address = address;
+
+	ret = kstrtol(tok, 16, &mask);
+	if (ret) {
+		ret = -EFAULT;
+		goto err;
+	}
+	tok = strsep(&inbuf, " ");
+	if (!tok) {
+		ret = -EFAULT;
+		goto err;
+	}
+	ret = kstrtol(tok, 16, &value);
+	if (!tok) {
+		ret = -EFAULT;
+		goto err;
+	}
+	ret = zynqmp_pm_config_reg_access(CONFIG_REG_WRITE, address,
+					  mask, value, NULL);
+	if (ret)
+		pr_err("unable to write value to %lx\n", value);
+err:
+	kfree(kern_buff);
+	if (ret)
+		return ret;
+	return count;
+}
+
+/**
+ * config_reg_show - Read config_reg sysfs attribute
+ * @kobj:	Kobject structure
+ * @attr:	Kobject attribute structure
+ * @buf:	User entered health_status attribute string
+ *
+ * User-space interface for getting the config register.
+ *
+ * To Read any CSU/PMU register, write address to the variable like below
+ * echo <address> > /sys/firmware/zynqmp/config_reg
+ *
+ * Then Read the address using below command
+ * cat /sys/firmware/zynqmp/config_reg
+ *
+ * Return: number of chars written to buf.
+ */
+static ssize_t config_reg_show(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       char *buf)
+{
+	int ret;
+	u32 ret_payload[PAYLOAD_ARG_CNT];
+
+	ret = zynqmp_pm_config_reg_access(CONFIG_REG_READ, register_address,
+					  0, 0, ret_payload);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", ret_payload[1]);
+}
+
+static struct kobj_attribute zynqmp_attr_config_reg =
+					__ATTR_RW(config_reg);
+
+static struct attribute *attrs[] = {
+	&zynqmp_attr_config_reg.attr,
+	NULL,
+};
+
+static const struct attribute_group attr_group = {
+	.attrs = attrs,
+	NULL,
+};
+
+static int zynqmp_pm_sysfs_init(void)
+{
+	struct kobject *zynqmp_kobj;
+	int ret;
+
+	zynqmp_kobj = kobject_create_and_add("zynqmp", firmware_kobj);
+	if (!zynqmp_kobj) {
+		pr_err("zynqmp: Firmware kobj add failed.\n");
+		return -ENOMEM;
+	}
+
+	ret = sysfs_create_group(zynqmp_kobj, &attr_group);
+	if (ret) {
+		pr_err("%s() sysfs creation fail with error %d\n",
+		       __func__, ret);
+	}
+
+	return ret;
+}
+
 static int zynqmp_firmware_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -748,6 +925,12 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
 	/* Assign eemi_ops_table */
 	eemi_ops_tbl = &eemi_ops;
 
+	ret = zynqmp_pm_sysfs_init();
+	if (ret) {
+		pr_err("%s() sysfs init fail with error %d\n", __func__, ret);
+		return ret;
+	}
+
 	zynqmp_pm_api_debugfs_init();
 
 	ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE, firmware_devs,
diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
index df366f1..55561d0 100644
--- a/include/linux/firmware/xlnx-zynqmp.h
+++ b/include/linux/firmware/xlnx-zynqmp.h
@@ -77,6 +77,8 @@ enum pm_api_id {
 	PM_CLOCK_GETRATE,
 	PM_CLOCK_SETPARENT,
 	PM_CLOCK_GETPARENT,
+	/* PM_REGISTER_ACCESS API */
+	PM_REGISTER_ACCESS = 52,
 };
 
 /* PMU-FW return status codes */
@@ -261,6 +263,11 @@ enum tap_delay_type {
 	PM_TAPDELAY_OUTPUT,
 };
 
+enum pm_register_access_id {
+	CONFIG_REG_WRITE,
+	CONFIG_REG_READ,
+};
+
 /**
  * struct zynqmp_pm_query_data - PM query data
  * @qid:	query ID
@@ -305,6 +312,8 @@ struct zynqmp_eemi_ops {
 			       const u32 capabilities,
 			       const u32 qos,
 			       const enum zynqmp_pm_request_ack ack);
+	int (*register_access)(u32 register_access_id, u32 address,
+			       u32 mask, u32 value, u32 *out);
 };
 
 int zynqmp_pm_invoke_fn(u32 pm_api_id, u32 arg0, u32 arg1,
-- 
2.7.4

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