drivers: jtag: Add JTAG core driver

JTAG class driver provide infrastructure to support hardware/software
JTAG platform drivers. It provide user layer API interface for flashing
and debugging external devices which equipped with JTAG interface
using standard transactions.

Driver exposes set of IOCTL to user space for:
- XFER:
  SIR (Scan Instruction Register, IEEE 1149.1 Data Register scan);
  SDR (Scan Data Register, IEEE 1149.1 Instruction Register scan);
- GIOCSTATUS read the current TAPC state of the JTAG controller
- SIOCSTATE Forces the JTAG TAPC to go into a particular state.
- SIOCFREQ/GIOCFREQ for setting and reading JTAG frequency.
- IOCBITBANG for low level control of JTAG signals.

Driver core provides set of internal APIs for allocation and
registration:
- jtag_register;
- jtag_unregister;
- jtag_alloc;
- jtag_free;

Platform driver on registration with jtag-core creates the next
entry in dev folder:
/dev/jtagX

Signed-off-by: Oleksandr Shamray <oleksandrs@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ernesto Corona <ernesto.corona@intel.com>
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Johan Hovold <johan@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: Federico Vaga <federico.vaga@cern.ch>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Christian Gromm <christian.gromm@microchip.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Yiwei Zhang <zzyiwei@google.com>
Cc: Alessandro Rubini <rubini@gnudd.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Steven Filary <steven.a.filary@intel.com>
Cc: Vadim Pasternak <vadimp@mellanox.com>
Cc: Amithash Prasad <amithash@fb.com>
Cc: Patrick Williams <patrickw3@fb.com>
Cc: Rgrs <rgrs@protonmail.com>

3 files changed, 339 insertions, 0 deletions

diff --git a/drivers/jtag/Kconfig b/drivers/jtag/Kconfig
new file mode 100644
index 000000000000..47771fcd3c5b
--- /dev/null
+++ b/drivers/jtag/Kconfig
@@ -0,0 +1,17 @@
+menuconfig JTAG
+	tristate "JTAG support"
+	help
+	  This provides basic core functionality support for JTAG class devices.
+	  Hardware that is equipped with a JTAG microcontroller can be
+	  supported by using this driver's interfaces.
+	  This driver exposes a set of IOCTLs to the user space for
+	  the following commands:
+	    SDR: Performs an IEEE 1149.1 Data Register scan
+	    SIR: Performs an IEEE 1149.1 Instruction Register scan.
+	    RUNTEST: Forces the IEEE 1149.1 bus to a run state for a specified
+	    number of clocks or a specified time period.
+
+	  If you want this support, you should say Y here.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called jtag.
diff --git a/drivers/jtag/Makefile b/drivers/jtag/Makefile
new file mode 100644
index 000000000000..af374939a9e6
--- /dev/null
+++ b/drivers/jtag/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_JTAG)		+= jtag.o
diff --git a/drivers/jtag/jtag.c b/drivers/jtag/jtag.c
new file mode 100644
index 000000000000..39a4d88a9c21
--- /dev/null
+++ b/drivers/jtag/jtag.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2018 Mellanox Technologies. All rights reserved.
+// Copyright (c) 2018 Oleksandr Shamray <oleksandrs@mellanox.com>
+// Copyright (c) 2019 Intel Corporation
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/jtag.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/rtnetlink.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <uapi/linux/jtag.h>
+
+struct jtag {
+	struct miscdevice miscdev;
+	const struct jtag_ops *ops;
+	int id;
+	unsigned long priv[0];
+};
+
+static DEFINE_IDA(jtag_ida);
+
+void *jtag_priv(struct jtag *jtag)
+{
+	return jtag->priv;
+}
+EXPORT_SYMBOL_GPL(jtag_priv);
+
+static long jtag_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct jtag *jtag = file->private_data;
+	struct jtag_tap_state tapstate;
+	struct jtag_xfer xfer;
+	struct bitbang_packet bitbang;
+	struct tck_bitbang *bitbang_data;
+	struct jtag_mode mode;
+	u8 *xfer_data;
+	u32 data_size;
+	u32 value;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+
+	switch (cmd) {
+	case JTAG_GIOCFREQ:
+		if (!jtag->ops->freq_get)
+			return -EOPNOTSUPP;
+
+		err = jtag->ops->freq_get(jtag, &value);
+		if (err)
+			break;
+
+		if (put_user(value, (__u32 __user *)arg))
+			err = -EFAULT;
+		break;
+
+	case JTAG_SIOCFREQ:
+		if (!jtag->ops->freq_set)
+			return -EOPNOTSUPP;
+
+		if (get_user(value, (__u32 __user *)arg))
+			return -EFAULT;
+		if (value == 0)
+			return -EINVAL;
+
+		err = jtag->ops->freq_set(jtag, value);
+		break;
+
+	case JTAG_SIOCSTATE:
+		if (copy_from_user(&tapstate, (const void __user *)arg,
+				   sizeof(struct jtag_tap_state)))
+			return -EFAULT;
+
+		if (tapstate.from > JTAG_STATE_CURRENT)
+			return -EINVAL;
+
+		if (tapstate.endstate > JTAG_STATE_CURRENT)
+			return -EINVAL;
+
+		if (tapstate.reset > JTAG_FORCE_RESET)
+			return -EINVAL;
+
+		err = jtag->ops->status_set(jtag, &tapstate);
+		break;
+
+	case JTAG_IOCXFER:
+		if (copy_from_user(&xfer, (const void __user *)arg,
+				   sizeof(struct jtag_xfer)))
+			return -EFAULT;
+
+		if (xfer.length >= JTAG_MAX_XFER_DATA_LEN)
+			return -EINVAL;
+
+		if (xfer.type > JTAG_SDR_XFER)
+			return -EINVAL;
+
+		if (xfer.direction > JTAG_READ_WRITE_XFER)
+			return -EINVAL;
+
+		if (xfer.from > JTAG_STATE_CURRENT)
+			return -EINVAL;
+
+		if (xfer.endstate > JTAG_STATE_CURRENT)
+			return -EINVAL;
+
+		data_size = DIV_ROUND_UP(xfer.length, BITS_PER_BYTE);
+		xfer_data = memdup_user(u64_to_user_ptr(xfer.tdio), data_size);
+		if (IS_ERR(xfer_data))
+			return -EFAULT;
+
+		err = jtag->ops->xfer(jtag, &xfer, xfer_data);
+		if (err) {
+			kfree(xfer_data);
+			return err;
+		}
+
+		err = copy_to_user(u64_to_user_ptr(xfer.tdio),
+				   (void *)xfer_data, data_size);
+		kfree(xfer_data);
+		if (err)
+			return -EFAULT;
+
+		if (copy_to_user((void __user *)arg, (void *)&xfer,
+				 sizeof(struct jtag_xfer)))
+			return -EFAULT;
+		break;
+
+	case JTAG_GIOCSTATUS:
+		err = jtag->ops->status_get(jtag, &value);
+		if (err)
+			break;
+
+		err = put_user(value, (__u32 __user *)arg);
+		break;
+	case JTAG_IOCBITBANG:
+		if (copy_from_user(&bitbang, (const void __user *)arg,
+				   sizeof(struct bitbang_packet)))
+			return -EFAULT;
+
+		if (bitbang.length >= JTAG_MAX_XFER_DATA_LEN)
+			return -EINVAL;
+
+		data_size = bitbang.length * sizeof(struct tck_bitbang);
+		bitbang_data = memdup_user((void __user *)bitbang.data,
+					   data_size);
+		if (IS_ERR(bitbang_data))
+			return -EFAULT;
+
+		err = jtag->ops->bitbang(jtag, &bitbang, bitbang_data);
+		if (err) {
+			kfree(bitbang_data);
+			return err;
+		}
+		err = copy_to_user((void __user *)bitbang.data,
+				   (void *)bitbang_data, data_size);
+		kfree(bitbang_data);
+		if (err)
+			return -EFAULT;
+		break;
+	case JTAG_SIOCMODE:
+		if (!jtag->ops->mode_set)
+			return -EOPNOTSUPP;
+
+		if (copy_from_user(&mode, (const void __user *)arg,
+				   sizeof(struct jtag_mode)))
+			return -EFAULT;
+
+		err = jtag->ops->mode_set(jtag, &mode);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+	return err;
+}
+
+static int jtag_open(struct inode *inode, struct file *file)
+{
+	struct jtag *jtag = container_of(file->private_data,
+					 struct jtag,
+					 miscdev);
+
+	file->private_data = jtag;
+	if (jtag->ops->enable(jtag))
+		return -EBUSY;
+	return nonseekable_open(inode, file);
+}
+
+static int jtag_release(struct inode *inode, struct file *file)
+{
+	struct jtag *jtag = file->private_data;
+
+	if (jtag->ops->disable(jtag))
+		return -EBUSY;
+	return 0;
+}
+
+static const struct file_operations jtag_fops = {
+	.owner		= THIS_MODULE,
+	.open		= jtag_open,
+	.llseek		= noop_llseek,
+	.unlocked_ioctl	= jtag_ioctl,
+	.release	= jtag_release,
+};
+
+struct jtag *jtag_alloc(struct device *host, size_t priv_size,
+			const struct jtag_ops *ops)
+{
+	struct jtag *jtag;
+
+	if (!host)
+		return NULL;
+
+	if (!ops)
+		return NULL;
+
+	if (!ops->status_set || !ops->status_get || !ops->xfer)
+		return NULL;
+
+	jtag = kzalloc(sizeof(*jtag) + priv_size, GFP_KERNEL);
+	if (!jtag)
+		return NULL;
+
+	jtag->ops = ops;
+	jtag->miscdev.parent = host;
+
+	return jtag;
+}
+EXPORT_SYMBOL_GPL(jtag_alloc);
+
+void jtag_free(struct jtag *jtag)
+{
+	kfree(jtag);
+}
+EXPORT_SYMBOL_GPL(jtag_free);
+
+static int jtag_register(struct jtag *jtag)
+{
+	struct device *dev = jtag->miscdev.parent;
+	int err;
+	int id;
+
+	if (!dev)
+		return -ENODEV;
+
+	id = ida_simple_get(&jtag_ida, 0, 0, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	jtag->id = id;
+
+	jtag->miscdev.fops =  &jtag_fops;
+	jtag->miscdev.minor = MISC_DYNAMIC_MINOR;
+	jtag->miscdev.name = kasprintf(GFP_KERNEL, "jtag%d", id);
+	if (!jtag->miscdev.name) {
+		err = -ENOMEM;
+		goto err_jtag_alloc;
+	}
+
+	err = misc_register(&jtag->miscdev);
+	if (err) {
+		dev_err(jtag->miscdev.parent, "Unable to register device\n");
+		goto err_jtag_name;
+	}
+	return 0;
+
+err_jtag_name:
+	kfree(jtag->miscdev.name);
+err_jtag_alloc:
+	ida_simple_remove(&jtag_ida, id);
+	return err;
+}
+
+static void jtag_unregister(struct jtag *jtag)
+{
+	misc_deregister(&jtag->miscdev);
+	kfree(jtag->miscdev.name);
+	ida_simple_remove(&jtag_ida, jtag->id);
+}
+
+static void devm_jtag_unregister(struct device *dev, void *res)
+{
+	jtag_unregister(*(struct jtag **)res);
+}
+
+int devm_jtag_register(struct device *dev, struct jtag *jtag)
+{
+	struct jtag **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_jtag_unregister, sizeof(struct jtag *),
+			   GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = jtag_register(jtag);
+	if (!ret) {
+		*ptr = jtag;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_jtag_register);
+
+static void __exit jtag_exit(void)
+{
+	ida_destroy(&jtag_ida);
+}
+
+module_exit(jtag_exit);
+
+MODULE_AUTHOR("Oleksandr Shamray <oleksandrs@mellanox.com>");
+MODULE_DESCRIPTION("Generic jtag support");
+MODULE_LICENSE("GPL v2");