firmware: xilinx: Add sysfs interface

Add firmware-ggs sysfs interface which provides read/write
interface to global storage registers.
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
Link: https://lore.kernel.org/r/1587761887-4279-23-git-send-email-jolly.shah@xilinx.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/stable/sysfs-driver-firmware-zynqmp

+What:		/sys/devices/platform/firmware\:zynqmp-firmware/ggs*
+Date:		March 2020
+KernelVersion:	5.6
+Contact:	"Jolly Shah" <jollys@xilinx.com>
+Description:
+		Read/Write PMU global general storage register value,
+		GLOBAL_GEN_STORAGE{0:3}.
+		Global general storage register that can be used
+		by system to pass information between masters.
+
+		The register is reset during system or power-on
+		resets. Three registers are used by the FSBL and
+		other Xilinx software products: GLOBAL_GEN_STORAGE{4:6}.
+
+		Usage:
+		# cat /sys/devices/platform/firmware\:zynqmp-firmware/ggs0
+		# echo <value> > /sys/devices/platform/firmware\:zynqmp-firmware/ggs0
+
+		Example:
+		# cat /sys/devices/platform/firmware\:zynqmp-firmware/ggs0
+		# echo 0x1234ABCD > /sys/devices/platform/firmware\:zynqmp-firmware/ggs0
+
+Users:		Xilinx
+
+What:		/sys/devices/platform/firmware\:zynqmp-firmware/pggs*
+Date:		March 2020
+KernelVersion:	5.6
+Contact:	"Jolly Shah" <jollys@xilinx.com>
+Description:
+		Read/Write PMU persistent global general storage register
+		value, PERS_GLOB_GEN_STORAGE{0:3}.
+		Persistent global general storage register that
+		can be used by system to pass information between
+		masters.
+
+		This register is only reset by the power-on reset
+		and maintains its value through a system reset.
+		Four registers are used by the FSBL and other Xilinx
+		software products: PERS_GLOB_GEN_STORAGE{4:7}.
+		Register is reset only by a POR reset.
+
+		Usage:
+		# cat /sys/devices/platform/firmware\:zynqmp-firmware/pggs0
+		# echo <value> > /sys/devices/platform/firmware\:zynqmp-firmware/pggs0
+
+		Example:
+		# cat /sys/devices/platform/firmware\:zynqmp-firmware/pggs0
+		# echo 0x1234ABCD > /sys/devices/platform/firmware\:zynqmp-firmware/pggs0
+
+Users:		Xilinx

drivers/firmware/xilinx/zynqmp.c

@@ -2,7 +2,7 @@
 /*
  * Xilinx Zynq MPSoC Firmware layer
  *
- *  Copyright (C) 2014-2018 Xilinx, Inc.
+ *  Copyright (C) 2014-2020 Xilinx, Inc.
  *
  *  Michal Simek <michal.simek@xilinx.com>
  *  Davorin Mista <davorin.mista@aggios.com>
@@ -875,6 +875,170 @@ int zynqmp_pm_aes_engine(const u64 address, u32 *out)
 }
 EXPORT_SYMBOL_GPL(zynqmp_pm_aes_engine);
 
+static ssize_t ggs_show(struct device *device,
+			struct device_attribute *attr,
+			char *buf,
+			u32 reg)
+{
+	int ret;
+	u32 ret_payload[PAYLOAD_ARG_CNT];
+
+	ret = zynqmp_pm_read_ggs(reg, ret_payload);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", ret_payload[1]);
+}
+
+static ssize_t ggs_store(struct device *device,
+			 struct device_attribute *attr,
+			 const char *buf, size_t count,
+			 u32 reg)
+{
+	long value;
+	int ret;
+
+	if (reg >= GSS_NUM_REGS)
+		return -EINVAL;
+
+	ret = kstrtol(buf, 16, &value);
+	if (ret) {
+		count = -EFAULT;
+		goto err;
+	}
+
+	ret = zynqmp_pm_write_ggs(reg, value);
+	if (ret)
+		count = -EFAULT;
+
+err:
+	return count;
+}
+
+/* GGS register show functions */
+#define GGS0_SHOW(N)						\
+	ssize_t ggs##N##_show(struct device *device,		\
+			      struct device_attribute *attr,	\
+			      char *buf)			\
+	{							\
+		return ggs_show(device, attr, buf, N);		\
+	}
+
+static GGS0_SHOW(0);
+static GGS0_SHOW(1);
+static GGS0_SHOW(2);
+static GGS0_SHOW(3);
+
+/* GGS register store function */
+#define GGS0_STORE(N)						\
+	ssize_t ggs##N##_store(struct device *device,		\
+			       struct device_attribute *attr,	\
+			       const char *buf,			\
+			       size_t count)			\
+	{							\
+		return ggs_store(device, attr, buf, count, N);	\
+	}
+
+static GGS0_STORE(0);
+static GGS0_STORE(1);
+static GGS0_STORE(2);
+static GGS0_STORE(3);
+
+static ssize_t pggs_show(struct device *device,
+			 struct device_attribute *attr,
+			 char *buf,
+			 u32 reg)
+{
+	int ret;
+	u32 ret_payload[PAYLOAD_ARG_CNT];
+
+	ret = zynqmp_pm_read_pggs(reg, ret_payload);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", ret_payload[1]);
+}
+
+static ssize_t pggs_store(struct device *device,
+			  struct device_attribute *attr,
+			  const char *buf, size_t count,
+			  u32 reg)
+{
+	long value;
+	int ret;
+
+	if (reg >= GSS_NUM_REGS)
+		return -EINVAL;
+
+	ret = kstrtol(buf, 16, &value);
+	if (ret) {
+		count = -EFAULT;
+		goto err;
+	}
+
+	ret = zynqmp_pm_write_pggs(reg, value);
+	if (ret)
+		count = -EFAULT;
+
+err:
+	return count;
+}
+
+#define PGGS0_SHOW(N)						\
+	ssize_t pggs##N##_show(struct device *device,		\
+			       struct device_attribute *attr,	\
+			       char *buf)			\
+	{							\
+		return pggs_show(device, attr, buf, N);		\
+	}
+
+#define PGGS0_STORE(N)						\
+	ssize_t pggs##N##_store(struct device *device,		\
+				struct device_attribute *attr,	\
+				const char *buf,		\
+				size_t count)			\
+	{							\
+		return pggs_store(device, attr, buf, count, N);	\
+	}
+
+/* PGGS register show functions */
+static PGGS0_SHOW(0);
+static PGGS0_SHOW(1);
+static PGGS0_SHOW(2);
+static PGGS0_SHOW(3);
+
+/* PGGS register store functions */
+static PGGS0_STORE(0);
+static PGGS0_STORE(1);
+static PGGS0_STORE(2);
+static PGGS0_STORE(3);
+
+/* GGS register attributes */
+static DEVICE_ATTR_RW(ggs0);
+static DEVICE_ATTR_RW(ggs1);
+static DEVICE_ATTR_RW(ggs2);
+static DEVICE_ATTR_RW(ggs3);
+
+/* PGGS register attributes */
+static DEVICE_ATTR_RW(pggs0);
+static DEVICE_ATTR_RW(pggs1);
+static DEVICE_ATTR_RW(pggs2);
+static DEVICE_ATTR_RW(pggs3);
+
+static struct attribute *zynqmp_firmware_attrs[] = {
+	&dev_attr_ggs0.attr,
+	&dev_attr_ggs1.attr,
+	&dev_attr_ggs2.attr,
+	&dev_attr_ggs3.attr,
+	&dev_attr_pggs0.attr,
+	&dev_attr_pggs1.attr,
+	&dev_attr_pggs2.attr,
+	&dev_attr_pggs3.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(zynqmp_firmware);
+
 static int zynqmp_firmware_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -952,6 +1116,7 @@ static struct platform_driver zynqmp_firmware_driver = {
 	.driver = {
 		.name = "zynqmp_firmware",
 		.of_match_table = zynqmp_firmware_of_match,
+		.dev_groups = zynqmp_firmware_groups,
 	},
 	.probe = zynqmp_firmware_probe,
 	.remove = zynqmp_firmware_remove,

include/linux/firmware/xlnx-zynqmp.h

@@ -42,6 +42,8 @@
 
 #define ZYNQMP_PM_MAX_QOS		100U
 
+#define GSS_NUM_REGS	(4)
+
 /* Node capabilities */
 #define	ZYNQMP_PM_CAPABILITY_ACCESS	0x1U
 #define	ZYNQMP_PM_CAPABILITY_CONTEXT	0x2U