staging: comedi: comedi_8254: introduce module for 8254 timer support

A 8254 timer/counter is commonly used on data acquisition boards to provide
the internal pacer clock used to acquire analog input samples. Some boards
also to allow the timers to be used externally.

Currently the 8254 timers are supported by comedi using the 8253.h header
and a number of inline functions. This works for the internal pacer clock
but requires the drivers to implement subdevice code necessary to use the
timers externally.

Introduce a new module to support both the internal pacer clock and the
external counter subdevice. This will allow removing a bunch of duplicated
code in the drivers and standardizes the comedi 8254 timer support.

This implementation is based on the 8253.h inline functions and the various
subdevice functionality in the comedi drivers.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/Kconfig

@@ -1222,6 +1222,9 @@ config COMEDI_VMK80XX
 
 endif # COMEDI_USB_DRIVERS
 
+config COMEDI_8254
+	tristate
+
 config COMEDI_8255
 	tristate "Generic 8255 support"
 	---help---

drivers/staging/comedi/drivers/Makefile

@@ -3,6 +3,7 @@
 ccflags-$(CONFIG_COMEDI_DEBUG)		:= -DDEBUG
 
 # Comedi "helper" modules
+obj-$(CONFIG_COMEDI_8254)		+= comedi_8254.o
 obj-$(CONFIG_COMEDI_ISADMA)		+= comedi_isadma.o
 
 # Comedi misc drivers

drivers/staging/comedi/drivers/comedi_8254.h

+/*
+ * comedi_8254.h
+ * Generic 8254 timer/counter support
+ * Copyright (C) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 2000 David A. Schleef <ds@schleef.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _COMEDI_8254_H
+#define _COMEDI_8254_H
+
+/*
+ * Common oscillator base values in nanoseconds
+ */
+#define I8254_OSC_BASE_10MHZ	100
+#define I8254_OSC_BASE_5MHZ	200
+#define I8254_OSC_BASE_4MHZ	250
+#define I8254_OSC_BASE_2MHZ	500
+#define I8254_OSC_BASE_1MHZ	1000
+#define I8254_OSC_BASE_100KHZ	10000
+#define I8254_OSC_BASE_10KHZ	100000
+#define I8254_OSC_BASE_1KHZ	1000000
+
+/*
+ * I/O access size used to read/write registers
+ */
+#define I8254_IO8		1
+#define I8254_IO16		2
+#define I8254_IO32		4
+
+/*
+ * Register map for generic 8254 timer (I8254_IO8 with 0 regshift)
+ */
+#define I8254_COUNTER0_REG		0x00
+#define I8254_COUNTER1_REG		0x01
+#define I8254_COUNTER2_REG		0x02
+#define I8254_CTRL_REG			0x03
+#define I8254_CTRL_SEL_CTR(x)		((x) << 6)
+#define I8254_CTRL_READBACK_COUNT	((3 << 6) | (1 << 4))
+#define I8254_CTRL_READBACK_STATUS	((3 << 6) | (1 << 5))
+#define I8254_CTRL_READBACK_SEL_CTR(x)	(2 << (x))
+#define I8254_CTRL_LATCH		(0 << 4)
+#define I8254_CTRL_LSB_ONLY		(1 << 4)
+#define I8254_CTRL_MSB_ONLY		(2 << 4)
+#define I8254_CTRL_LSB_MSB		(3 << 4)
+
+/* counter maps zero to 0x10000 */
+#define I8254_MAX_COUNT			0x10000
+
+/**
+ * struct comedi_8254 - private data used by this module
+ * @iobase:		PIO base address of the registers (in/out)
+ * @mmio:		MMIO base address of the registers (read/write)
+ * @iosize:		I/O size used to access the registers (b/w/l)
+ * @regshift:		register gap shift
+ * @osc_base:		cascaded oscillator speed in ns
+ * @divisor:		divisor for single counter
+ * @divisor1:		divisor loaded into first cascaded counter
+ * @divisor2:		divisor loaded into second cascaded counter
+ * #next_div:		next divisor for single counter
+ * @next_div1:		next divisor to use for first cascaded counter
+ * @next_div2:		next divisor to use for second cascaded counter
+ * @busy:		flags used to indicate that a counter is "busy"
+ * @insn_config:	driver specific (*insn_config) callback
+ */
+struct comedi_8254 {
+	unsigned long iobase;
+	void __iomem *mmio;
+	unsigned int iosize;
+	unsigned int regshift;
+	unsigned int osc_base;
+	unsigned int divisor;
+	unsigned int divisor1;
+	unsigned int divisor2;
+	unsigned int next_div;
+	unsigned int next_div1;
+	unsigned int next_div2;
+	bool busy[3];
+
+	int (*insn_config)(struct comedi_device *, struct comedi_subdevice *s,
+			   struct comedi_insn *, unsigned int *data);
+};
+
+unsigned int comedi_8254_status(struct comedi_8254 *, unsigned int counter);
+unsigned int comedi_8254_read(struct comedi_8254 *, unsigned int counter);
+void comedi_8254_write(struct comedi_8254 *,
+		       unsigned int counter, unsigned int val);
+
+int comedi_8254_set_mode(struct comedi_8254 *,
+			 unsigned int counter, unsigned int mode);
+int comedi_8254_load(struct comedi_8254 *,
+		     unsigned int counter, unsigned int val, unsigned int mode);
+
+void comedi_8254_pacer_enable(struct comedi_8254 *,
+			      unsigned int counter1, unsigned int counter2,
+			      bool enable);
+void comedi_8254_update_divisors(struct comedi_8254 *);
+void comedi_8254_cascade_ns_to_timer(struct comedi_8254 *,
+				     unsigned int *nanosec, unsigned int flags);
+void comedi_8254_ns_to_timer(struct comedi_8254 *,
+			     unsigned int *nanosec, unsigned int flags);
+
+void comedi_8254_set_busy(struct comedi_8254 *,
+			  unsigned int counter, bool busy);
+
+void comedi_8254_subdevice_init(struct comedi_subdevice *,
+				struct comedi_8254 *);
+
+struct comedi_8254 *comedi_8254_init(unsigned long iobase,
+				     unsigned int osc_base,
+				     unsigned int iosize,
+				     unsigned int regshift);
+struct comedi_8254 *comedi_8254_mm_init(void __iomem *mmio,
+					unsigned int osc_base,
+					unsigned int iosize,
+					unsigned int regshift);
+
+#endif	/* _COMEDI_8254_H */