staging: gpib: Add GPIB common core driver

This is the common core driver that interfaces with the userland code
and creates the gpib device files.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20240918121908.19366-6-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gpib/common/Makefile

@@ -0,0 +1,6 @@
+
+obj-m += gpib_common.o
+
+gpib_common-objs := gpib_os.o iblib.o
+
+

drivers/staging/gpib/common/iblib.c

@@ -0,0 +1,740 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/***************************************************************************
+ *    copyright            : (C) 2001, 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+#include "ibsys.h"
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/vmalloc.h>
+
+/*
+ * IBCAC
+ * Return to the controller active state from the
+ * controller standby state, i.e., turn ATN on.  Note
+ * that in order to enter the controller active state
+ * from the controller idle state, ibsic must be called.
+ * If sync is non-zero, attempt to take control synchronously.
+ * If fallback_to_async is non-zero, try to take control asynchronously
+ * if synchronous attempt fails.
+ */
+int ibcac(gpib_board_t *board, int sync, int fallback_to_async)
+{
+	int status = ibstatus(board);
+	int retval;
+
+	if ((status & CIC) == 0) {
+		pr_err("gpib: not CIC during %s()\n", __func__);
+		return -1;
+	}
+
+	if (status & ATN)
+		return 0;
+
+	if (sync && (status & LACS) == 0)
+		/* tcs (take control synchronously) can only possibly work when
+		 *  controller is listener.  Error code also needs to be -ETIMEDOUT
+		 *  or it will giveout without doing fallback.
+		 */
+		retval = -ETIMEDOUT;
+	else
+		retval = board->interface->take_control(board, sync);
+
+	if (retval < 0 && fallback_to_async) {
+		if (sync && retval == -ETIMEDOUT)
+			retval = board->interface->take_control(board, 0);
+	}
+	board->interface->update_status(board, 0);
+
+	return retval;
+}
+
+/* After ATN is asserted, it should cause any connected devices
+ * to start listening for command bytes and leave acceptor idle state.
+ * So if ATN is asserted and neither NDAC or NRFD are asserted,
+ * then there are no devices and ibcmd should error out immediately.
+ * Some gpib hardware sees itself asserting NDAC/NRFD when it
+ * is controller in charge, in which case this check will
+ * do nothing useful (but shouldn't cause any harm either).
+ * Drivers that don't need this check (ni_usb for example) may
+ * set the skip_check_for_command_acceptors flag in their
+ * gpib_interface_struct to avoid useless overhead.
+ */
+static int check_for_command_acceptors(gpib_board_t *board)
+{
+	int lines;
+
+	if (board->interface->skip_check_for_command_acceptors)
+		return 0;
+	if (!board->interface->line_status)
+		return 0;
+
+	udelay(2); // allow time for devices to respond to ATN if it was just asserted
+
+	lines = board->interface->line_status(board);
+	if (lines < 0)
+		return lines;
+
+	if (lines & ValidATN) {
+		if ((lines & BusATN) == 0) {
+			pr_err("gpib: ATN not asserted in %s()?", __func__);
+			return 0;
+		}
+	}
+
+	if ((lines & ValidNRFD) && (lines & ValidNDAC))	{
+		if ((lines & BusNRFD) == 0 && (lines & BusNDAC) == 0)
+			return -ENOTCONN;
+	}
+
+	return 0;
+}
+
+/*
+ * IBCMD
+ * Write cnt command bytes from buf to the GPIB.  The
+ * command operation terminates only on I/O complete.
+ *
+ * NOTE:
+ *      1.  Prior to beginning the command, the interface is
+ *          placed in the controller active state.
+ *      2.  Before calling ibcmd for the first time, ibsic
+ *          must be called to initialize the GPIB and enable
+ *          the interface to leave the controller idle state.
+ */
+int ibcmd(gpib_board_t *board, uint8_t *buf, size_t length, size_t *bytes_written)
+{
+	ssize_t ret = 0;
+	int status;
+
+	*bytes_written = 0;
+
+	status = ibstatus(board);
+
+	if ((status & CIC) == 0) {
+		pr_err("gpib: cannot send command when not controller-in-charge\n");
+		return -EIO;
+	}
+
+	os_start_timer(board, board->usec_timeout);
+
+	ret = ibcac(board, 1, 1);
+	if (ret == 0) {
+		ret = check_for_command_acceptors(board);
+		if (ret == 0)
+			ret = board->interface->command(board, buf, length, bytes_written);
+	}
+
+	os_remove_timer(board);
+
+	if (io_timed_out(board))
+		ret = -ETIMEDOUT;
+
+	return ret;
+}
+
+/*
+ * IBGTS
+ * Go to the controller standby state from the controller
+ * active state, i.e., turn ATN off.
+ */
+
+int ibgts(gpib_board_t *board)
+{
+	int status = ibstatus(board);
+	int retval;
+
+	if ((status & CIC) == 0) {
+		pr_err("gpib: not CIC during %s()\n", __func__);
+		return -1;
+	}
+
+	retval = board->interface->go_to_standby(board);    /* go to standby */
+	if (retval < 0)
+		pr_err("gpib: error while going to standby\n");
+
+	board->interface->update_status(board, 0);
+
+	return retval;
+}
+
+static int autospoll_wait_should_wake_up(gpib_board_t *board)
+{
+	int retval;
+
+	mutex_lock(&board->big_gpib_mutex);
+
+	retval = board->master && board->autospollers > 0 &&
+		!atomic_read(&board->stuck_srq) &&
+		test_and_clear_bit(SRQI_NUM, &board->status);
+
+	mutex_unlock(&board->big_gpib_mutex);
+	return retval;
+}
+
+static int autospoll_thread(void *board_void)
+{
+	gpib_board_t *board = board_void;
+	int retval = 0;
+
+	GPIB_DPRINTK("entering autospoll thread\n");
+
+	while (1) {
+		wait_event_interruptible(board->wait,
+					 kthread_should_stop() ||
+					 autospoll_wait_should_wake_up(board));
+		GPIB_DPRINTK("autospoll wait satisfied\n");
+		if (kthread_should_stop())
+			break;
+
+		mutex_lock(&board->big_gpib_mutex);
+		/* make sure we are still good after we have lock */
+		if (board->autospollers <= 0 || board->master == 0) {
+			mutex_unlock(&board->big_gpib_mutex);
+			continue;
+		}
+		mutex_unlock(&board->big_gpib_mutex);
+
+		if (try_module_get(board->provider_module)) {
+			retval = autopoll_all_devices(board);
+			module_put(board->provider_module);
+		} else {
+			pr_err("gpib%i: %s: try_module_get() failed!\n", board->minor, __func__);
+		}
+		if (retval <= 0) {
+			pr_err("gpib%i: %s: stuck SRQ\n", board->minor, __func__);
+
+			atomic_set(&board->stuck_srq, 1);	// XXX could be better
+			set_bit(SRQI_NUM, &board->status);
+		}
+	}
+	pr_info("gpib%i: exiting autospoll thread\n", board->minor);
+	return retval;
+}
+
+int ibonline(gpib_board_t *board)
+{
+	int retval;
+
+	if (board->online)
+		return -EBUSY;
+	if (!board->interface)
+		return -ENODEV;
+	retval = gpib_allocate_board(board);
+	if (retval < 0)
+		return retval;
+
+	board->dev = NULL;
+	board->local_ppoll_mode = 0;
+	retval = board->interface->attach(board, &board->config);
+	if (retval < 0) {
+		board->interface->detach(board);
+		pr_err("gpib: interface attach failed\n");
+		return retval;
+	}
+	/* nios2nommu on 2.6.11 uclinux kernel has weird problems
+	 * with autospoll thread causing huge slowdowns
+	 */
+#ifndef CONFIG_NIOS2
+	board->autospoll_task = kthread_run(&autospoll_thread, board,
+					    "gpib%d_autospoll_kthread", board->minor);
+	retval = IS_ERR(board->autospoll_task);
+	if (retval) {
+		pr_err("gpib: failed to create autospoll thread\n");
+		board->interface->detach(board);
+		return retval;
+	}
+#endif
+	board->online = 1;
+	GPIB_DPRINTK("gpib: board online\n");
+
+	return 0;
+}
+
+/* XXX need to make sure board is generally not in use (grab board lock?) */
+int iboffline(gpib_board_t *board)
+{
+	int retval;
+
+	if (board->online == 0)
+		return 0;
+	if (!board->interface)
+		return -ENODEV;
+
+	if (board->autospoll_task && !IS_ERR(board->autospoll_task)) {
+		retval = kthread_stop(board->autospoll_task);
+		if (retval)
+			pr_err("gpib: kthread_stop returned %i\n", retval);
+		board->autospoll_task = NULL;
+	}
+
+	board->interface->detach(board);
+	gpib_deallocate_board(board);
+	board->online = 0;
+	GPIB_DPRINTK("gpib: board offline\n");
+
+	return 0;
+}
+
+/*
+ * IBLINES
+ * Poll the GPIB control lines and return their status in buf.
+ *
+ *      LSB (bits 0-7)  -  VALID lines mask (lines that can be monitored).
+ * Next LSB (bits 8-15) - STATUS lines mask (lines that are currently set).
+ *
+ */
+int iblines(const gpib_board_t *board, short *lines)
+{
+	int retval;
+
+	*lines = 0;
+	if (!board->interface->line_status)
+		return 0;
+	retval = board->interface->line_status(board);
+	if (retval < 0)
+		return retval;
+	*lines = retval;
+	return 0;
+}
+
+/*
+ * IBRD
+ * Read up to 'length' bytes of data from the GPIB into buf.  End
+ * on detection of END (EOI and or EOS) and set 'end_flag'.
+ *
+ * NOTE:
+ *      1.  The interface is placed in the controller standby
+ *          state prior to beginning the read.
+ *      2.  Prior to calling ibrd, the intended devices as well
+ *          as the interface board itself must be addressed by
+ *          calling ibcmd.
+ */
+
+int ibrd(gpib_board_t *board, uint8_t *buf, size_t length, int *end_flag, size_t *nbytes)
+{
+	ssize_t ret = 0;
+	int retval;
+	size_t bytes_read;
+
+	*nbytes = 0;
+	*end_flag = 0;
+	if (length == 0) {
+		pr_warn("gpib: %s() called with zero length?\n",  __func__);
+		return 0;
+	}
+
+	if (board->master) {
+		retval = ibgts(board);
+		if (retval < 0)
+			return retval;
+	}
+	/* XXX resetting timer here could cause timeouts take longer than they should,
+	 * since read_ioctl calls this
+	 * function in a loop, there is probably a similar problem with writes/commands
+	 */
+	os_start_timer(board, board->usec_timeout);
+
+	do {
+		ret = board->interface->read(board, buf, length - *nbytes, end_flag, &bytes_read);
+		if (ret < 0) {
+			pr_err("gpib read error\n");
+			goto ibrd_out;
+		}
+		buf += bytes_read;
+		*nbytes += bytes_read;
+		if (need_resched())
+			schedule();
+	} while (ret == 0 && *nbytes > 0 && *nbytes < length && *end_flag == 0);
+ibrd_out:
+	os_remove_timer(board);
+
+	return ret;
+}
+
+/*
+ * IBRPP
+ * Conduct a parallel poll and return the byte in buf.
+ *
+ * NOTE:
+ *	1.  Prior to conducting the poll the interface is placed
+ *	    in the controller active state.
+ */
+int ibrpp(gpib_board_t *board, uint8_t *result)
+{
+	int retval = 0;
+
+	os_start_timer(board, board->usec_timeout);
+	retval = ibcac(board, 1, 1);
+	if (retval)
+		return -1;
+
+	if (board->interface->parallel_poll(board, result)) {
+		pr_err("gpib: parallel poll failed\n");
+		retval = -1;
+	}
+	os_remove_timer(board);
+	return retval;
+}
+
+int ibppc(gpib_board_t *board, uint8_t configuration)
+{
+	configuration &= 0x1f;
+	board->interface->parallel_poll_configure(board, configuration);
+	board->parallel_poll_configuration = configuration;
+
+	return 0;
+}
+
+int ibrsv2(gpib_board_t *board, uint8_t status_byte, int new_reason_for_service)
+{
+	int board_status = ibstatus(board);
+	const unsigned int MSS = status_byte & request_service_bit;
+
+	if ((board_status & CIC)) {
+		pr_err("gpib: interface requested service while CIC\n");
+		return -EINVAL;
+	}
+
+	if (MSS == 0 && new_reason_for_service)
+		return -EINVAL;
+
+	if (board->interface->serial_poll_response2)	{
+		board->interface->serial_poll_response2(board, status_byte, new_reason_for_service);
+		// fall back on simpler serial_poll_response if the behavior would be the same
+	} else if (board->interface->serial_poll_response &&
+		   (MSS == 0 || (MSS && new_reason_for_service))) {
+		board->interface->serial_poll_response(board, status_byte);
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+/*
+ * IBSIC
+ * Send IFC for at least 100 microseconds.
+ *
+ * NOTE:
+ *	1.  Ibsic must be called prior to the first call to
+ *	    ibcmd in order to initialize the bus and enable the
+ *	    interface to leave the controller idle state.
+ */
+int ibsic(gpib_board_t *board, unsigned int usec_duration)
+{
+	if (board->master == 0)	{
+		pr_err("gpib: tried to assert IFC when not system controller\n");
+		return -1;
+	}
+
+	if (usec_duration < 100)
+		usec_duration = 100;
+	if (usec_duration > 1000) {
+		usec_duration = 1000;
+		pr_warn("gpib: warning, shortening long udelay\n");
+	}
+
+	GPIB_DPRINTK("sending interface clear\n");
+	board->interface->interface_clear(board, 1);
+	udelay(usec_duration);
+	board->interface->interface_clear(board, 0);
+
+	return 0;
+}
+
+void ibrsc(gpib_board_t *board, int request_control)
+{
+	board->master = request_control != 0;
+	if (!board->interface->request_system_control)	{
+		pr_err("gpib: bug! driver does not implement request_system_control()\n");
+		return;
+	}
+	board->interface->request_system_control(board, request_control);
+}
+
+/*
+ * IBSRE
+ * Send REN true if v is non-zero or false if v is zero.
+ */
+int ibsre(gpib_board_t *board, int enable)
+{
+	if (board->master == 0)	{
+		pr_err("gpib: tried to set REN when not system controller\n");
+		return -1;
+	}
+
+	board->interface->remote_enable(board, enable);	/* set or clear REN */
+	if (!enable)
+		usleep_range(100, 150);
+
+	return 0;
+}
+
+/*
+ * IBPAD
+ * change the GPIB address of the interface board.  The address
+ * must be 0 through 30.  ibonl resets the address to PAD.
+ */
+int ibpad(gpib_board_t *board, unsigned int addr)
+{
+	if (addr > 30) {
+		pr_err("gpib: invalid primary address %u\n", addr);
+		return -1;
+	}
+	board->pad = addr;
+	if (board->online)
+		board->interface->primary_address(board, board->pad);
+	GPIB_DPRINTK("set primary addr to %i\n", board->pad);
+	return 0;
+}
+
+/*
+ * IBSAD
+ * change the secondary GPIB address of the interface board.
+ * The address must be 0 through 30, or negative disables.  ibonl resets the
+ * address to SAD.
+ */
+int ibsad(gpib_board_t *board, int addr)
+{
+	if (addr > 30) {
+		pr_err("gpib: invalid secondary address %i, must be 0-30\n", addr);
+		return -1;
+	}
+	board->sad = addr;
+	if (board->online) {
+		if (board->sad >= 0)
+			board->interface->secondary_address(board, board->sad, 1);
+		else
+			board->interface->secondary_address(board, 0, 0);
+	}
+	GPIB_DPRINTK("set secondary addr to %i\n", board->sad);
+
+	return 0;
+}
+
+/*
+ * IBEOS
+ * Set the end-of-string modes for I/O operations to v.
+ *
+ */
+int ibeos(gpib_board_t *board, int eos, int eosflags)
+{
+	int retval;
+
+	if (eosflags & ~EOS_MASK) {
+		pr_err("bad EOS modes\n");
+		return -EINVAL;
+	}
+	if (eosflags & REOS) {
+		retval = board->interface->enable_eos(board, eos, eosflags & BIN);
+	} else {
+		board->interface->disable_eos(board);
+		retval = 0;
+	}
+	return retval;
+}
+
+int ibstatus(gpib_board_t *board)
+{
+	return general_ibstatus(board, NULL, 0, 0, NULL);
+}
+
+int general_ibstatus(gpib_board_t *board, const gpib_status_queue_t *device,
+		     int clear_mask, int set_mask, gpib_descriptor_t *desc)
+{
+	int status = 0;
+	short line_status;
+
+	if (board->private_data) {
+		status = board->interface->update_status(board, clear_mask);
+		/* XXX should probably stop having drivers use TIMO bit in
+		 * board->status to avoid confusion
+		 */
+		status &= ~TIMO;
+		/* get real SRQI status if we can */
+		if (iblines(board, &line_status) == 0) {
+			if ((line_status & ValidSRQ)) {
+				if ((line_status & BusSRQ))
+					status |= SRQI;
+				else
+					status &= ~SRQI;
+			}
+		}
+	}
+	if (device)
+		if (num_status_bytes(device))
+			status |= RQS;
+
+	if (desc) {
+		if (set_mask & CMPL)
+			atomic_set(&desc->io_in_progress, 0);
+		else if (clear_mask & CMPL)
+			atomic_set(&desc->io_in_progress, 1);
+
+		if (atomic_read(&desc->io_in_progress))
+			status &= ~CMPL;
+		else
+			status |= CMPL;
+	}
+	if (num_gpib_events(&board->event_queue))
+		status |= EVENT;
+	else
+		status &= ~EVENT;
+
+	return status;
+}
+
+struct wait_info {
+	gpib_board_t *board;
+	struct timer_list timer;
+	int timed_out;
+	unsigned long usec_timeout;
+};
+
+static void wait_timeout(struct timer_list *t)
+{
+	struct wait_info *winfo = from_timer(winfo, t, timer);
+
+	winfo->timed_out = 1;
+	wake_up_interruptible(&winfo->board->wait);
+}
+
+static void init_wait_info(struct wait_info *winfo)
+{
+	winfo->board = NULL;
+	winfo->timed_out = 0;
+	timer_setup_on_stack(&winfo->timer, wait_timeout, 0);
+}
+
+static int wait_satisfied(struct wait_info *winfo, gpib_status_queue_t *status_queue,
+			  int wait_mask, int *status, gpib_descriptor_t *desc)
+{
+	gpib_board_t *board = winfo->board;
+	int temp_status;
+
+	if (mutex_lock_interruptible(&board->big_gpib_mutex))
+		return -ERESTARTSYS;
+
+	temp_status = general_ibstatus(board, status_queue, 0, 0, desc);
+
+	mutex_unlock(&board->big_gpib_mutex);
+
+	if (winfo->timed_out)
+		temp_status |= TIMO;
+	else
+		temp_status &= ~TIMO;
+	if (wait_mask & temp_status) {
+		*status = temp_status;
+		return 1;
+	}
+//XXX does wait for END work?
+	return 0;
+}
+
+/* install timer interrupt handler */
+static void start_wait_timer(struct wait_info *winfo)
+/* Starts the timeout task  */
+{
+	winfo->timed_out = 0;
+
+	if (winfo->usec_timeout > 0)
+		mod_timer(&winfo->timer, jiffies + usec_to_jiffies(winfo->usec_timeout));
+}
+
+static void remove_wait_timer(struct wait_info *winfo)
+{
+	del_timer_sync(&winfo->timer);
+	destroy_timer_on_stack(&winfo->timer);
+}
+
+/*
+ * IBWAIT
+ * Check or wait for a GPIB event to occur.  The mask argument
+ * is a bit vector corresponding to the status bit vector.  It
+ * has a bit set for each condition which can terminate the wait
+ * If the mask is 0 then
+ * no condition is waited for.
+ */
+int ibwait(gpib_board_t *board, int wait_mask, int clear_mask, int set_mask,
+	   int *status, unsigned long usec_timeout, gpib_descriptor_t *desc)
+{
+	int retval = 0;
+	gpib_status_queue_t *status_queue;
+	struct wait_info winfo;
+
+	if (desc->is_board)
+		status_queue = NULL;
+	else
+		status_queue = get_gpib_status_queue(board, desc->pad, desc->sad);
+
+	if (wait_mask == 0) {
+		*status = general_ibstatus(board, status_queue, clear_mask, set_mask, desc);
+		return 0;
+	}
+
+	mutex_unlock(&board->big_gpib_mutex);
+
+	init_wait_info(&winfo);
+	winfo.board = board;
+	winfo.usec_timeout = usec_timeout;
+	start_wait_timer(&winfo);
+
+	if (wait_event_interruptible(board->wait, wait_satisfied(&winfo, status_queue,
+								 wait_mask, status, desc))) {
+		GPIB_DPRINTK("wait interrupted\n");
+		retval = -ERESTARTSYS;
+	}
+	remove_wait_timer(&winfo);
+
+	if (retval)
+		return retval;
+	if (mutex_lock_interruptible(&board->big_gpib_mutex))
+		return -ERESTARTSYS;
+
+	/* make sure we only clear status bits that we are reporting */
+	if (*status & clear_mask || set_mask)
+		general_ibstatus(board, status_queue, *status & clear_mask, set_mask, 0);
+
+	return 0;
+}
+
+/*
+ * IBWRT
+ * Write cnt bytes of data from buf to the GPIB.  The write
+ * operation terminates only on I/O complete.
+ *
+ * NOTE:
+ *      1.  Prior to beginning the write, the interface is
+ *          placed in the controller standby state.
+ *      2.  Prior to calling ibwrt, the intended devices as
+ *          well as the interface board itself must be
+ *          addressed by calling ibcmd.
+ */
+int ibwrt(gpib_board_t *board, uint8_t *buf, size_t cnt, int send_eoi, size_t *bytes_written)
+{
+	int ret = 0;
+	int retval;
+
+	if (cnt == 0) {
+		pr_warn("gpib: %s() called with zero length?\n", __func__);
+		return 0;
+	}
+
+	if (board->master) {
+		retval = ibgts(board);
+		if (retval < 0)
+			return retval;
+	}
+	os_start_timer(board, board->usec_timeout);
+	ret = board->interface->write(board, buf, cnt, send_eoi, bytes_written);
+
+	if (io_timed_out(board))
+		ret = -ETIMEDOUT;
+
+	os_remove_timer(board);
+
+	return ret;
+}
+

drivers/staging/gpib/common/ibsys.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include "gpibP.h"
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/major.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/timer.h>
+
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <asm/irq.h>
+#include <asm/dma.h>
+
+int gpib_allocate_board(gpib_board_t *board);
+void gpib_deallocate_board(gpib_board_t *board);
+
+unsigned int num_status_bytes(const gpib_status_queue_t *dev);
+int push_status_byte(gpib_status_queue_t *device, uint8_t poll_byte);
+int pop_status_byte(gpib_status_queue_t *device, uint8_t *poll_byte);
+gpib_status_queue_t *get_gpib_status_queue(gpib_board_t *board, unsigned int pad, int sad);
+int get_serial_poll_byte(gpib_board_t *board, unsigned int pad, int sad,
+			 unsigned int usec_timeout, uint8_t *poll_byte);
+int autopoll_all_devices(gpib_board_t *board);