[PATCH v5 1/2] tty/serial_core: add ISO7816 infrastructure

From: Ludovic Desroches
Date: Wed Sep 26 2018 - 09:02:45 EST

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From: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>

Add the ISO7816 ioctl and associated accessors and data structure.
Drivers can then use this common implementation to handle ISO7816
(smart cards).

Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
[ludovic.desroches@xxxxxxxxxxxxx: squash and rebase, removal of gpios, checkpatch fixes]
Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
---
Documentation/serial/serial-iso7816.txt | 83 +++++++++++++++++++++++++++++++++
arch/alpha/include/uapi/asm/ioctls.h | 2 +
arch/mips/include/uapi/asm/ioctls.h | 2 +
arch/parisc/include/uapi/asm/ioctls.h | 2 +
arch/powerpc/include/uapi/asm/ioctls.h | 2 +
arch/sh/include/uapi/asm/ioctls.h | 2 +
arch/sparc/include/uapi/asm/ioctls.h | 2 +
arch/xtensa/include/uapi/asm/ioctls.h | 2 +
drivers/tty/serial/serial_core.c | 60 ++++++++++++++++++++++++
include/linux/serial_core.h | 3 ++
include/uapi/asm-generic/ioctls.h | 2 +
include/uapi/linux/serial.h | 17 +++++++
12 files changed, 179 insertions(+)
create mode 100644 Documentation/serial/serial-iso7816.txt

diff --git a/Documentation/serial/serial-iso7816.txt b/Documentation/serial/serial-iso7816.txt
new file mode 100644
index 000000000000..3193d24a2b0f
--- /dev/null
+++ b/Documentation/serial/serial-iso7816.txt
@@ -0,0 +1,83 @@
+ ISO7816 SERIAL COMMUNICATIONS
+
+1. INTRODUCTION
+
+ ISO/IEC7816 is a series of standards specifying integrated circuit cards (ICC)
+ also known as smart cards.
+
+2. HARDWARE-RELATED CONSIDERATIONS
+
+ Some CPUs/UARTs (e.g., Microchip AT91) contain a built-in mode capable of
+ handling communication with a smart card.
+
+ For these microcontrollers, the Linux driver should be made capable of
+ working in both modes, and proper ioctls (see later) should be made
+ available at user-level to allow switching from one mode to the other, and
+ vice versa.
+
+3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL
+
+ The Linux kernel provides the serial_iso7816 structure (see [1]) to handle
+ ISO7816 communications. This data structure is used to set and configure
+ ISO7816 parameters in ioctls.
+
+ Any driver for devices capable of working both as RS232 and ISO7816 should
+ implement the iso7816_config callback in the uart_port structure. The
+ serial_core calls iso7816_config to do the device specific part in response
+ to TIOCGISO7816 and TIOCSISO7816 ioctls (see below). The iso7816_config
+ callback receives a pointer to struct serial_iso7816.
+
+4. USAGE FROM USER-LEVEL
+
+ From user-level, ISO7816 configuration can be get/set using the previous
+ ioctls. For instance, to set ISO7816 you can use the following code:
+
+ #include <linux/serial.h>
+
+ /* Include definition for ISO7816 ioctls: TIOCSISO7816 and TIOCGISO7816 */
+ #include <sys/ioctl.h>
+
+ /* Open your specific device (e.g., /dev/mydevice): */
+ int fd = open ("/dev/mydevice", O_RDWR);
+ if (fd < 0) {
+ /* Error handling. See errno. */
+ }
+
+ struct serial_iso7816 iso7816conf;
+
+ /* Reserved fields as to be zeroed */
+ memset(&iso7816conf, 0, sizeof(iso7816conf));
+
+ /* Enable ISO7816 mode: */
+ iso7816conf.flags |= SER_ISO7816_ENABLED;
+
+ /* Select the protocol: */
+ /* T=0 */
+ iso7816conf.flags |= SER_ISO7816_T(0);
+ /* or T=1 */
+ iso7816conf.flags |= SER_ISO7816_T(1);
+
+ /* Set the guard time: */
+ iso7816conf.tg = 2;
+
+ /* Set the clock frequency*/
+ iso7816conf.clk = 3571200;
+
+ /* Set transmission factors: */
+ iso7816conf.sc_fi = 372;
+ iso7816conf.sc_di = 1;
+
+ if (ioctl(fd_usart, TIOCSISO7816, &iso7816conf) < 0) {
+ /* Error handling. See errno. */
+ }
+
+ /* Use read() and write() syscalls here... */
+
+ /* Close the device when finished: */
+ if (close (fd) < 0) {
+ /* Error handling. See errno. */
+ }
+
+5. REFERENCES
+
+ [1] include/uapi/linux/serial.h
diff --git a/arch/alpha/include/uapi/asm/ioctls.h b/arch/alpha/include/uapi/asm/ioctls.h
index 3729d92d3fa8..1e9121c9b3c7 100644
--- a/arch/alpha/include/uapi/asm/ioctls.h
+++ b/arch/alpha/include/uapi/asm/ioctls.h
@@ -102,6 +102,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff --git a/arch/mips/include/uapi/asm/ioctls.h b/arch/mips/include/uapi/asm/ioctls.h
index 890245a9f0c4..16aa8a766aec 100644
--- a/arch/mips/include/uapi/asm/ioctls.h
+++ b/arch/mips/include/uapi/asm/ioctls.h
@@ -93,6 +93,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

/* I hope the range from 0x5480 on is free ... */
#define TIOCSCTTY 0x5480 /* become controlling tty */
diff --git a/arch/parisc/include/uapi/asm/ioctls.h b/arch/parisc/include/uapi/asm/ioctls.h
index aafb1c0ca0af..82d1148c6379 100644
--- a/arch/parisc/include/uapi/asm/ioctls.h
+++ b/arch/parisc/include/uapi/asm/ioctls.h
@@ -62,6 +62,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define FIONCLEX 0x5450 /* these numbers need to be adjusted. */
#define FIOCLEX 0x5451
diff --git a/arch/powerpc/include/uapi/asm/ioctls.h b/arch/powerpc/include/uapi/asm/ioctls.h
index 41b1a5c15734..2c145da3b774 100644
--- a/arch/powerpc/include/uapi/asm/ioctls.h
+++ b/arch/powerpc/include/uapi/asm/ioctls.h
@@ -102,6 +102,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define TIOCSERCONFIG 0x5453
#define TIOCSERGWILD 0x5454
diff --git a/arch/sh/include/uapi/asm/ioctls.h b/arch/sh/include/uapi/asm/ioctls.h
index cc62f6f98103..11866d4f60e1 100644
--- a/arch/sh/include/uapi/asm/ioctls.h
+++ b/arch/sh/include/uapi/asm/ioctls.h
@@ -95,6 +95,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define TIOCSERCONFIG _IO('T', 83) /* 0x5453 */
#define TIOCSERGWILD _IOR('T', 84, int) /* 0x5454 */
diff --git a/arch/sparc/include/uapi/asm/ioctls.h b/arch/sparc/include/uapi/asm/ioctls.h
index 2df52711e170..7fd2f5873c9e 100644
--- a/arch/sparc/include/uapi/asm/ioctls.h
+++ b/arch/sparc/include/uapi/asm/ioctls.h
@@ -27,6 +27,8 @@
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGRS485 _IOR('T', 0x41, struct serial_rs485)
#define TIOCSRS485 _IOWR('T', 0x42, struct serial_rs485)
+#define TIOCGISO7816 _IOR('T', 0x43, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x44, struct serial_iso7816)

/* Note that all the ioctls that are not available in Linux have a
* double underscore on the front to: a) avoid some programs to
diff --git a/arch/xtensa/include/uapi/asm/ioctls.h b/arch/xtensa/include/uapi/asm/ioctls.h
index ec43609cbfc5..6d4a87296c95 100644
--- a/arch/xtensa/include/uapi/asm/ioctls.h
+++ b/arch/xtensa/include/uapi/asm/ioctls.h
@@ -107,6 +107,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define TIOCSERCONFIG _IO('T', 83)
#define TIOCSERGWILD _IOR('T', 84, int)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 80bb56facfb6..70402cdb4d8c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1308,6 +1308,58 @@ static int uart_set_rs485_config(struct uart_port *port,
return 0;
}

+static int uart_get_iso7816_config(struct uart_port *port,
+ struct serial_iso7816 __user *iso7816)
+{
+ unsigned long flags;
+ struct serial_iso7816 aux;
+
+ if (!port->iso7816_config)
+ return -ENOIOCTLCMD;
+
+ spin_lock_irqsave(&port->lock, flags);
+ aux = port->iso7816;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (copy_to_user(iso7816, &aux, sizeof(aux)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int uart_set_iso7816_config(struct uart_port *port,
+ struct serial_iso7816 __user *iso7816_user)
+{
+ struct serial_iso7816 iso7816;
+ int i, ret;
+ unsigned long flags;
+
+ if (!port->iso7816_config)
+ return -ENOIOCTLCMD;
+
+ if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
+ return -EFAULT;
+
+ /*
+ * There are 5 words reserved for future use. Check that userspace
+ * doesn't put stuff in there to prevent breakages in the future.
+ */
+ for (i = 0; i < 5; i++)
+ if (iso7816.reserved[i])
+ return -EINVAL;
+
+ spin_lock_irqsave(&port->lock, flags);
+ ret = port->iso7816_config(port, &iso7816);
+ spin_unlock_irqrestore(&port->lock, flags);
+ if (ret)
+ return ret;
+
+ if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
+ return -EFAULT;
+
+ return 0;
+}
+
/*
* Called via sys_ioctl. We can use spin_lock_irq() here.
*/
@@ -1392,6 +1444,14 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
case TIOCSRS485:
ret = uart_set_rs485_config(uport, uarg);
break;
+
+ case TIOCSISO7816:
+ ret = uart_set_iso7816_config(state->uart_port, uarg);
+ break;
+
+ case TIOCGISO7816:
+ ret = uart_get_iso7816_config(state->uart_port, uarg);
+ break;
default:
if (uport->ops->ioctl)
ret = uport->ops->ioctl(uport, cmd, arg);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 406edae44ca3..047fa67d039b 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -144,6 +144,8 @@ struct uart_port {
void (*handle_break)(struct uart_port *);
int (*rs485_config)(struct uart_port *,
struct serial_rs485 *rs485);
+ int (*iso7816_config)(struct uart_port *,
+ struct serial_iso7816 *iso7816);
unsigned int irq; /* irq number */
unsigned long irqflags; /* irq flags */
unsigned int uartclk; /* base uart clock */
@@ -260,6 +262,7 @@ struct uart_port {
struct attribute_group *attr_group; /* port specific attributes */
const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
struct serial_rs485 rs485;
+ struct serial_iso7816 iso7816;
void *private_data; /* generic platform data pointer */
};

diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
index 040651735662..cdc9f4ca8c27 100644
--- a/include/uapi/asm-generic/ioctls.h
+++ b/include/uapi/asm-generic/ioctls.h
@@ -79,6 +79,8 @@
#define TIOCGPTLCK _IOR('T', 0x39, int) /* Get Pty lock state */
#define TIOCGEXCL _IOR('T', 0x40, int) /* Get exclusive mode state */
#define TIOCGPTPEER _IO('T', 0x41) /* Safely open the slave */
+#define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816)
+#define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816)

#define FIONCLEX 0x5450
#define FIOCLEX 0x5451
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 3fdd0dee8b41..93eb3c496ff1 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -132,4 +132,21 @@ struct serial_rs485 {
are a royal PITA .. */
};

+/*
+ * Serial interface for controlling ISO7816 settings on chips with suitable
+ * support. Set with TIOCSISO7816 and get with TIOCGISO7816 if supported by
+ * your platform.
+ */
+struct serial_iso7816 {
+ __u32 flags; /* ISO7816 feature flags */
+#define SER_ISO7816_ENABLED (1 << 0)
+#define SER_ISO7816_T_PARAM (0x0f << 4)
+#define SER_ISO7816_T(t) (((t) & 0x0f) << 4)
+ __u32 tg;
+ __u32 sc_fi;
+ __u32 sc_di;
+ __u32 clk;
+ __u32 reserved[5];
+};
+
#endif /* _UAPI_LINUX_SERIAL_H */
--
2.12.2

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