Merge drm/drm-next into drm-intel-next-queued

Catch up with upstream, in particular to get c1e8d7c6a7a6 ("mmap locking
API: convert mmap_sem comments").

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

36 files changed, 1117 insertions, 226 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index d4665fe9ccd2..98c3a5d8003e 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -11,7 +11,7 @@ config TTY_PRINTK
 	tristate "TTY driver to output user messages via printk"
 	depends on EXPERT && TTY
 	default n
-	---help---
+	help
 	  If you say Y here, the support for writing user messages (i.e.
 	  console messages) via printk is available.
 
@@ -33,7 +33,7 @@ config TTY_PRINTK_LEVEL
 config PRINTER
 	tristate "Parallel printer support"
 	depends on PARPORT
-	---help---
+	help
 	  If you intend to attach a printer to the parallel port of your Linux
 	  box (as opposed to using a serial printer; if the connector at the
 	  printer has 9 or 25 holes ["female"], then it's serial), say Y.
@@ -59,7 +59,7 @@ config PRINTER
 config LP_CONSOLE
 	bool "Support for console on line printer"
 	depends on PRINTER
-	---help---
+	help
 	  If you want kernel messages to be printed out as they occur, you
 	  can have a console on the printer. This option adds support for
 	  doing that; to actually get it to happen you need to pass the
@@ -76,7 +76,7 @@ config LP_CONSOLE
 config PPDEV
 	tristate "Support for user-space parallel port device drivers"
 	depends on PARPORT
-	---help---
+	help
 	  Saying Y to this adds support for /dev/parport device nodes.  This
 	  is needed for programs that want portable access to the parallel
 	  port, for instance deviceid (which displays Plug-and-Play device
@@ -146,7 +146,7 @@ config DS1620
 config NWBUTTON
 	tristate "NetWinder Button"
 	depends on ARCH_NETWINDER
-	---help---
+	help
 	  If you say Y here and create a character device node /dev/nwbutton
 	  with major and minor numbers 10 and 158 ("man mknod"), then every
 	  time the orange button is pressed a number of times, the number of
@@ -182,7 +182,7 @@ config NWBUTTON_REBOOT
 config NWFLASH
 	tristate "NetWinder flash support"
 	depends on ARCH_NETWINDER
-	---help---
+	help
 	  If you say Y here and create a character device /dev/flash with
 	  major 10 and minor 160 you can manipulate the flash ROM containing
 	  the NetWinder firmware. Be careful as accidentally overwriting the
@@ -209,7 +209,7 @@ config DTLK
 
 config XILINX_HWICAP
 	tristate "Xilinx HWICAP Support"
-	depends on XILINX_VIRTEX || MICROBLAZE
+	depends on MICROBLAZE
 	help
 	  This option enables support for Xilinx Internal Configuration
 	  Access Port (ICAP) driver.  The ICAP is used on Xilinx Virtex
@@ -220,7 +220,7 @@ config XILINX_HWICAP
 config R3964
 	tristate "Siemens R3964 line discipline"
 	depends on TTY && BROKEN
-	---help---
+	help
 	  This driver allows synchronous communication with devices using the
 	  Siemens R3964 packet protocol. Unless you are dealing with special
 	  hardware like PLCs, you are unlikely to need this.
@@ -233,7 +233,7 @@ config R3964
 config APPLICOM
 	tristate "Applicom intelligent fieldbus card support"
 	depends on PCI
-	---help---
+	help
 	  This driver provides the kernel-side support for the intelligent
 	  fieldbus cards made by Applicom International. More information
 	  about these cards can be found on the WWW at the address
@@ -248,7 +248,7 @@ config APPLICOM
 config SONYPI
 	tristate "Sony Vaio Programmable I/O Control Device support"
 	depends on X86_32 && PCI && INPUT
-	---help---
+	help
 	  This driver enables access to the Sony Programmable I/O Control
 	  Device which can be found in many (all ?) Sony Vaio laptops.
 
@@ -269,7 +269,7 @@ config MWAVE
 	tristate "ACP Modem (Mwave) support"
 	depends on X86 && TTY
 	select SERIAL_8250
-	---help---
+	help
 	  The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
 	  kernel driver and a user level application. Together these components
 	  support direct attachment to public switched telephone networks (PSTNs)
@@ -347,7 +347,7 @@ config NVRAM
 	tristate "/dev/nvram support"
 	depends on X86 || HAVE_ARCH_NVRAM_OPS
 	default M68K || PPC
-	---help---
+	help
 	  If you say Y here and create a character special file /dev/nvram
 	  with major number 10 and minor number 144 using mknod ("man mknod"),
 	  you get read and write access to the non-volatile memory.
diff --git a/drivers/char/agp/Kconfig b/drivers/char/agp/Kconfig
index bc54235a7022..a086dd34f932 100644
--- a/drivers/char/agp/Kconfig
+++ b/drivers/char/agp/Kconfig
@@ -3,7 +3,7 @@ menuconfig AGP
 	tristate "/dev/agpgart (AGP Support)"
 	depends on ALPHA || IA64 || PARISC || PPC || X86
 	depends on PCI
-	---help---
+	help
 	  AGP (Accelerated Graphics Port) is a bus system mainly used to
 	  connect graphics cards to the rest of the system.
 
@@ -30,7 +30,7 @@ menuconfig AGP
 config AGP_ALI
 	tristate "ALI chipset support"
 	depends on AGP && X86_32
-	---help---
+	help
 	  This option gives you AGP support for the GLX component of
 	  X on the following ALi chipsets.  The supported chipsets
 	  include M1541, M1621, M1631, M1632, M1641,M1647,and M1651.
@@ -45,7 +45,7 @@ config AGP_ALI
 config AGP_ATI
 	tristate "ATI chipset support"
 	depends on AGP && X86_32
-	---help---
+	help
 	  This option gives you AGP support for the GLX component of
 	  X on the ATI RadeonIGP family of chipsets.
 
diff --git a/drivers/char/agp/frontend.c b/drivers/char/agp/frontend.c
index 47098648502d..00ff5fcb808a 100644
--- a/drivers/char/agp/frontend.c
+++ b/drivers/char/agp/frontend.c
@@ -39,7 +39,6 @@
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
-#include <asm/pgtable.h>
 #include "agp.h"
 
 struct agp_front_data agp_fe;
diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
index 9e84239f88d4..3ffbb1c80c5c 100644
--- a/drivers/char/agp/generic.c
+++ b/drivers/char/agp/generic.c
@@ -42,7 +42,6 @@
 #ifdef CONFIG_X86
 #include <asm/set_memory.h>
 #endif
-#include <asm/pgtable.h>
 #include "agp.h"
 
 __u32 *agp_gatt_table;
diff --git a/drivers/char/bsr.c b/drivers/char/bsr.c
index e5e5333f302d..cce2af5df7b4 100644
--- a/drivers/char/bsr.c
+++ b/drivers/char/bsr.c
@@ -17,7 +17,6 @@
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
-#include <asm/pgtable.h>
 #include <asm/io.h>
 
 /*
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 9bc46da8d77a..0ad17efc96df 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -6,7 +6,7 @@
 menuconfig HW_RANDOM
 	tristate "Hardware Random Number Generator Core support"
 	default m
-	---help---
+	help
 	  Hardware Random Number Generator Core infrastructure.
 
 	  To compile this driver as a module, choose M here: the
@@ -24,7 +24,7 @@ if HW_RANDOM
 config HW_RANDOM_TIMERIOMEM
 	tristate "Timer IOMEM HW Random Number Generator support"
 	depends on HAS_IOMEM
-	---help---
+	help
 	  This driver provides kernel-side support for a generic Random
 	  Number Generator used by reading a 'dumb' iomem address that
 	  is to be read no faster than, for example, once a second;
@@ -39,7 +39,7 @@ config HW_RANDOM_INTEL
 	tristate "Intel HW Random Number Generator support"
 	depends on (X86 || IA64) && PCI
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Intel i8xx-based motherboards.
 
@@ -52,7 +52,7 @@ config HW_RANDOM_AMD
 	tristate "AMD HW Random Number Generator support"
 	depends on (X86 || PPC_MAPLE) && PCI
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on AMD 76x-based motherboards.
 
@@ -65,7 +65,7 @@ config HW_RANDOM_ATMEL
 	tristate "Atmel Random Number Generator support"
 	depends on ARCH_AT91 && HAVE_CLK && OF
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Atmel AT91 devices.
 
@@ -79,7 +79,7 @@ config HW_RANDOM_BCM2835
 	depends on ARCH_BCM2835 || ARCH_BCM_NSP || ARCH_BCM_5301X || \
 		   ARCH_BCM_63XX || BCM63XX || BMIPS_GENERIC
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on the Broadcom BCM2835 and BCM63xx SoCs.
 
@@ -92,7 +92,7 @@ config HW_RANDOM_IPROC_RNG200
 	tristate "Broadcom iProc/STB RNG200 support"
 	depends on ARCH_BCM_IPROC || ARCH_BCM2835 || ARCH_BRCMSTB
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the RNG200
 	  hardware found on the Broadcom iProc and STB SoCs.
 
@@ -105,7 +105,7 @@ config HW_RANDOM_GEODE
 	tristate "AMD Geode HW Random Number Generator support"
 	depends on X86_32 && PCI
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on the AMD Geode LX.
 
@@ -118,7 +118,7 @@ config HW_RANDOM_N2RNG
 	tristate "Niagara2 Random Number Generator support"
 	depends on SPARC64
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Niagara2 cpus.
 
@@ -131,7 +131,7 @@ config HW_RANDOM_VIA
 	tristate "VIA HW Random Number Generator support"
 	depends on X86
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on VIA based motherboards.
 
@@ -144,7 +144,7 @@ config HW_RANDOM_IXP4XX
 	tristate "Intel IXP4xx NPU HW Pseudo-Random Number Generator support"
 	depends on ARCH_IXP4XX
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Pseudo-Random
 	  Number Generator hardware found on the Intel IXP45x/46x NPU.
 
@@ -157,7 +157,7 @@ config HW_RANDOM_OMAP
 	tristate "OMAP Random Number Generator support"
 	depends on ARCH_OMAP16XX || ARCH_OMAP2PLUS || ARCH_MVEBU
 	default HW_RANDOM
- 	---help---
+	help
  	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on OMAP16xx, OMAP2/3/4/5, AM33xx/AM43xx
 	  multimedia processors, and Marvell Armada 7k/8k SoCs.
@@ -171,7 +171,7 @@ config HW_RANDOM_OMAP3_ROM
 	tristate "OMAP3 ROM Random Number Generator support"
 	depends on ARCH_OMAP3
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on OMAP34xx processors.
 
@@ -184,7 +184,7 @@ config HW_RANDOM_OCTEON
 	tristate "Octeon Random Number Generator support"
 	depends on CAVIUM_OCTEON_SOC
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Octeon processors.
 
@@ -197,7 +197,7 @@ config HW_RANDOM_PASEMI
 	tristate "PA Semi HW Random Number Generator support"
 	depends on PPC_PASEMI
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on PA Semi PWRficient SoCs.
 
@@ -209,7 +209,7 @@ config HW_RANDOM_PASEMI
 config HW_RANDOM_VIRTIO
 	tristate "VirtIO Random Number Generator support"
 	depends on VIRTIO
-	---help---
+	help
 	  This driver provides kernel-side support for the virtual Random Number
 	  Generator hardware.
 
@@ -220,7 +220,7 @@ config HW_RANDOM_TX4939
 	tristate "TX4939 Random Number Generator support"
 	depends on SOC_TX4939
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on TX4939 SoC.
 
@@ -233,7 +233,7 @@ config HW_RANDOM_MXC_RNGA
 	tristate "Freescale i.MX RNGA Random Number Generator"
 	depends on SOC_IMX31
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Freescale i.MX processors.
 
@@ -247,7 +247,7 @@ config HW_RANDOM_IMX_RNGC
 	depends on HAS_IOMEM && HAVE_CLK
 	depends on SOC_IMX25 || COMPILE_TEST
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator Version C hardware found on some Freescale i.MX
 	  processors. Version B is also supported by this driver.
@@ -261,7 +261,7 @@ config HW_RANDOM_NOMADIK
 	tristate "ST-Ericsson Nomadik Random Number Generator support"
 	depends on ARCH_NOMADIK
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on ST-Ericsson SoCs (8815 and 8500).
 
@@ -274,7 +274,7 @@ config HW_RANDOM_PSERIES
 	tristate "pSeries HW Random Number Generator support"
 	depends on PPC64 && IBMVIO
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on POWER7+ machines and above
 
@@ -287,7 +287,7 @@ config HW_RANDOM_POWERNV
 	tristate "PowerNV Random Number Generator support"
 	depends on PPC_POWERNV
 	default HW_RANDOM
-	---help---
+	help
 	  This is the driver for Random Number Generator hardware found
 	  in POWER7+ and above machines for PowerNV platform.
 
@@ -300,7 +300,7 @@ config HW_RANDOM_HISI
 	tristate "Hisilicon Random Number Generator support"
 	depends on HW_RANDOM && ARCH_HISI
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Hisilicon Hip04 and Hip05 SoC.
 
@@ -325,7 +325,7 @@ config HW_RANDOM_HISI_V2
 config HW_RANDOM_ST
 	tristate "ST Microelectronics HW Random Number Generator support"
 	depends on HW_RANDOM && ARCH_STI
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on STi series of SoCs.
 
@@ -336,7 +336,7 @@ config HW_RANDOM_XGENE
 	tristate "APM X-Gene True Random Number Generator (TRNG) support"
 	depends on HW_RANDOM && ARCH_XGENE
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on APM X-Gene SoC.
 
@@ -363,7 +363,7 @@ config HW_RANDOM_PIC32
 	tristate "Microchip PIC32 Random Number Generator support"
 	depends on HW_RANDOM && MACH_PIC32
 	default y
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on a PIC32.
 
@@ -377,7 +377,7 @@ config HW_RANDOM_MESON
 	depends on HW_RANDOM
 	depends on ARCH_MESON || COMPILE_TEST
 	default y
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Amlogic Meson SoCs.
 
@@ -390,7 +390,7 @@ config HW_RANDOM_CAVIUM
 	tristate "Cavium ThunderX Random Number Generator support"
 	depends on HW_RANDOM && PCI && (ARM64 || (COMPILE_TEST && 64BIT))
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Cavium SoCs.
 
@@ -404,7 +404,7 @@ config HW_RANDOM_MTK
 	depends on HW_RANDOM
 	depends on ARCH_MEDIATEK || COMPILE_TEST
 	default y
-	---help---
+	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on Mediatek SoCs.
 
@@ -417,7 +417,7 @@ config HW_RANDOM_S390
 	tristate "S390 True Random Number Generator support"
 	depends on S390
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides kernel-side support for the True
 	  Random Number Generator available as CPACF extension
 	  on modern s390 hardware platforms.
@@ -431,7 +431,7 @@ config HW_RANDOM_EXYNOS
 	tristate "Samsung Exynos True Random Number Generator support"
 	depends on ARCH_EXYNOS || COMPILE_TEST
 	default HW_RANDOM
-	---help---
+	help
 	  This driver provides support for the True Random Number
 	  Generator available in Exynos SoCs.
 
@@ -474,6 +474,19 @@ config HW_RANDOM_KEYSTONE
 	help
 	  This option enables Keystone's hardware random generator.
 
+config HW_RANDOM_CCTRNG
+	tristate "Arm CryptoCell True Random Number Generator support"
+	depends on HAS_IOMEM && OF
+	help
+	  Say 'Y' to enable the True Random Number Generator driver for the
+	  Arm TrustZone CryptoCell family of processors.
+	  Currently the CryptoCell 713 and 703 are supported.
+	  The driver is supported only in SoC where Trusted Execution
+	  Environment is not used.
+	  Choose 'M' to compile this driver as a module. The module
+	  will be called cctrng.
+	  If unsure, say 'N'.
+
 endif # HW_RANDOM
 
 config UML_RANDOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index a7801b49ce6c..2c6724735345 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -41,3 +41,4 @@ obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
 obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
 obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o
 obj-$(CONFIG_HW_RANDOM_NPCM) += npcm-rng.o
+obj-$(CONFIG_HW_RANDOM_CCTRNG) += cctrng.o
diff --git a/drivers/char/hw_random/cctrng.c b/drivers/char/hw_random/cctrng.c
new file mode 100644
index 000000000000..619148fb2dc9
--- /dev/null
+++ b/drivers/char/hw_random/cctrng.c
@@ -0,0 +1,735 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2019-2020 ARM Limited or its affiliates. */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/workqueue.h>
+#include <linux/circ_buf.h>
+#include <linux/completion.h>
+#include <linux/of.h>
+#include <linux/bitfield.h>
+#include <linux/fips.h>
+
+#include "cctrng.h"
+
+#define CC_REG_LOW(name)  (name ## _BIT_SHIFT)
+#define CC_REG_HIGH(name) (CC_REG_LOW(name) + name ## _BIT_SIZE - 1)
+#define CC_GENMASK(name)  GENMASK(CC_REG_HIGH(name), CC_REG_LOW(name))
+
+#define CC_REG_FLD_GET(reg_name, fld_name, reg_val)     \
+	(FIELD_GET(CC_GENMASK(CC_ ## reg_name ## _ ## fld_name), reg_val))
+
+#define CC_HW_RESET_LOOP_COUNT 10
+#define CC_TRNG_SUSPEND_TIMEOUT 3000
+
+/* data circular buffer in words must be:
+ *  - of a power-of-2 size (limitation of circ_buf.h macros)
+ *  - at least 6, the size generated in the EHR according to HW implementation
+ */
+#define CCTRNG_DATA_BUF_WORDS 32
+
+/* The timeout for the TRNG operation should be calculated with the formula:
+ * Timeout = EHR_NUM * VN_COEFF * EHR_LENGTH * SAMPLE_CNT * SCALE_VALUE
+ * while:
+ *  - SAMPLE_CNT is input value from the characterisation process
+ *  - all the rest are constants
+ */
+#define EHR_NUM 1
+#define VN_COEFF 4
+#define EHR_LENGTH CC_TRNG_EHR_IN_BITS
+#define SCALE_VALUE 2
+#define CCTRNG_TIMEOUT(smpl_cnt) \
+	(EHR_NUM * VN_COEFF * EHR_LENGTH * smpl_cnt * SCALE_VALUE)
+
+struct cctrng_drvdata {
+	struct platform_device *pdev;
+	void __iomem *cc_base;
+	struct clk *clk;
+	struct hwrng rng;
+	u32 active_rosc;
+	/* Sampling interval for each ring oscillator:
+	 * count of ring oscillator cycles between consecutive bits sampling.
+	 * Value of 0 indicates non-valid rosc
+	 */
+	u32 smpl_ratio[CC_TRNG_NUM_OF_ROSCS];
+
+	u32 data_buf[CCTRNG_DATA_BUF_WORDS];
+	struct circ_buf circ;
+	struct work_struct compwork;
+	struct work_struct startwork;
+
+	/* pending_hw - 1 when HW is pending, 0 when it is idle */
+	atomic_t pending_hw;
+
+	/* protects against multiple concurrent consumers of data_buf */
+	spinlock_t read_lock;
+};
+
+
+/* functions for write/read CC registers */
+static inline void cc_iowrite(struct cctrng_drvdata *drvdata, u32 reg, u32 val)
+{
+	iowrite32(val, (drvdata->cc_base + reg));
+}
+static inline u32 cc_ioread(struct cctrng_drvdata *drvdata, u32 reg)
+{
+	return ioread32(drvdata->cc_base + reg);
+}
+
+
+static int cc_trng_pm_get(struct device *dev)
+{
+	int rc = 0;
+
+	rc = pm_runtime_get_sync(dev);
+
+	/* pm_runtime_get_sync() can return 1 as a valid return code */
+	return (rc == 1 ? 0 : rc);
+}
+
+static void cc_trng_pm_put_suspend(struct device *dev)
+{
+	int rc = 0;
+
+	pm_runtime_mark_last_busy(dev);
+	rc = pm_runtime_put_autosuspend(dev);
+	if (rc)
+		dev_err(dev, "pm_runtime_put_autosuspend returned %x\n", rc);
+}
+
+static int cc_trng_pm_init(struct cctrng_drvdata *drvdata)
+{
+	struct device *dev = &(drvdata->pdev->dev);
+
+	/* must be before the enabling to avoid redundant suspending */
+	pm_runtime_set_autosuspend_delay(dev, CC_TRNG_SUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(dev);
+	/* set us as active - note we won't do PM ops until cc_trng_pm_go()! */
+	return pm_runtime_set_active(dev);
+}
+
+static void cc_trng_pm_go(struct cctrng_drvdata *drvdata)
+{
+	struct device *dev = &(drvdata->pdev->dev);
+
+	/* enable the PM module*/
+	pm_runtime_enable(dev);
+}
+
+static void cc_trng_pm_fini(struct cctrng_drvdata *drvdata)
+{
+	struct device *dev = &(drvdata->pdev->dev);
+
+	pm_runtime_disable(dev);
+}
+
+
+static inline int cc_trng_parse_sampling_ratio(struct cctrng_drvdata *drvdata)
+{
+	struct device *dev = &(drvdata->pdev->dev);
+	struct device_node *np = drvdata->pdev->dev.of_node;
+	int rc;
+	int i;
+	/* ret will be set to 0 if at least one rosc has (sampling ratio > 0) */
+	int ret = -EINVAL;
+
+	rc = of_property_read_u32_array(np, "arm,rosc-ratio",
+					drvdata->smpl_ratio,
+					CC_TRNG_NUM_OF_ROSCS);
+	if (rc) {
+		/* arm,rosc-ratio was not found in device tree */
+		return rc;
+	}
+
+	/* verify that at least one rosc has (sampling ratio > 0) */
+	for (i = 0; i < CC_TRNG_NUM_OF_ROSCS; ++i) {
+		dev_dbg(dev, "rosc %d sampling ratio %u",
+			i, drvdata->smpl_ratio[i]);
+
+		if (drvdata->smpl_ratio[i] > 0)
+			ret = 0;
+	}
+
+	return ret;
+}
+
+static int cc_trng_change_rosc(struct cctrng_drvdata *drvdata)
+{
+	struct device *dev = &(drvdata->pdev->dev);
+
+	dev_dbg(dev, "cctrng change rosc (was %d)\n", drvdata->active_rosc);
+	drvdata->active_rosc += 1;
+
+	while (drvdata->active_rosc < CC_TRNG_NUM_OF_ROSCS) {
+		if (drvdata->smpl_ratio[drvdata->active_rosc] > 0)
+			return 0;
+
+		drvdata->active_rosc += 1;
+	}
+	return -EINVAL;
+}
+
+
+static void cc_trng_enable_rnd_source(struct cctrng_drvdata *drvdata)
+{
+	u32 max_cycles;
+
+	/* Set watchdog threshold to maximal allowed time (in CPU cycles) */
+	max_cycles = CCTRNG_TIMEOUT(drvdata->smpl_ratio[drvdata->active_rosc]);
+	cc_iowrite(drvdata, CC_RNG_WATCHDOG_VAL_REG_OFFSET, max_cycles);
+
+	/* enable the RND source */
+	cc_iowrite(drvdata, CC_RND_SOURCE_ENABLE_REG_OFFSET, 0x1);
+
+	/* unmask RNG interrupts */
+	cc_iowrite(drvdata, CC_RNG_IMR_REG_OFFSET, (u32)~CC_RNG_INT_MASK);
+}
+
+
+/* increase circular data buffer index (head/tail) */
+static inline void circ_idx_inc(int *idx, int bytes)
+{
+	*idx += (bytes + 3) >> 2;
+	*idx &= (CCTRNG_DATA_BUF_WORDS - 1);
+}
+
+static inline size_t circ_buf_space(struct cctrng_drvdata *drvdata)
+{
+	return CIRC_SPACE(drvdata->circ.head,
+			  drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+
+}
+
+static int cctrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	/* current implementation ignores "wait" */
+
+	struct cctrng_drvdata *drvdata = (struct cctrng_drvdata *)rng->priv;
+	struct device *dev = &(drvdata->pdev->dev);
+	u32 *buf = (u32 *)drvdata->circ.buf;
+	size_t copied = 0;
+	size_t cnt_w;
+	size_t size;
+	size_t left;
+
+	if (!spin_trylock(&drvdata->read_lock)) {
+		/* concurrent consumers from data_buf cannot be served */
+		dev_dbg_ratelimited(dev, "unable to hold lock\n");
+		return 0;
+	}
+
+	/* copy till end of data buffer (without wrap back) */
+	cnt_w = CIRC_CNT_TO_END(drvdata->circ.head,
+				drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+	size = min((cnt_w<<2), max);
+	memcpy(data, &(buf[drvdata->circ.tail]), size);
+	copied = size;
+	circ_idx_inc(&drvdata->circ.tail, size);
+	/* copy rest of data in data buffer */
+	left = max - copied;
+	if (left > 0) {
+		cnt_w = CIRC_CNT(drvdata->circ.head,
+				 drvdata->circ.tail, CCTRNG_DATA_BUF_WORDS);
+		size = min((cnt_w<<2), left);
+		memcpy(data, &(buf[drvdata->circ.tail]), size);
+		copied += size;
+		circ_idx_inc(&drvdata->circ.tail, size);
+	}
+
+	spin_unlock(&drvdata->read_lock);
+
+	if (circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) {
+		if (atomic_cmpxchg(&drvdata->pending_hw, 0, 1) == 0) {
+			/* re-check space in buffer to avoid potential race */
+			if (circ_buf_space(drvdata) >= CC_TRNG_EHR_IN_WORDS) {
+				/* increment device's usage counter */
+				int rc = cc_trng_pm_get(dev);
+
+				if (rc) {
+					dev_err(dev,
+						"cc_trng_pm_get returned %x\n",
+						rc);
+					return rc;
+				}
+
+				/* schedule execution of deferred work handler
+				 * for filling of data buffer
+				 */
+				schedule_work(&drvdata->startwork);
+			} else {
+				atomic_set(&drvdata->pending_hw, 0);
+			}
+		}
+	}
+
+	return copied;
+}
+
+static void cc_trng_hw_trigger(struct cctrng_drvdata *drvdata)
+{
+	u32 tmp_smpl_cnt = 0;
+	struct device *dev = &(drvdata->pdev->dev);
+
+	dev_dbg(dev, "cctrng hw trigger.\n");
+
+	/* enable the HW RND clock */
+	cc_iowrite(drvdata, CC_RNG_CLK_ENABLE_REG_OFFSET, 0x1);
+
+	/* do software reset */
+	cc_iowrite(drvdata, CC_RNG_SW_RESET_REG_OFFSET, 0x1);
+	/* in order to verify that the reset has completed,
+	 * the sample count need to be verified
+	 */
+	do {
+		/* enable the HW RND clock   */
+		cc_iowrite(drvdata, CC_RNG_CLK_ENABLE_REG_OFFSET, 0x1);
+
+		/* set sampling ratio (rng_clocks) between consecutive bits */