1 files changed, 287 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-i8255.c b/drivers/gpio/gpio-i8255.c
new file mode 100644
index 000000000..9b97db418
--- /dev/null
+++ b/drivers/gpio/gpio-i8255.c
@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel 8255 Programmable Peripheral Interface
+ * Copyright (C) 2022 William Breathitt Gray
+ */
+#include <linux/bitmap.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "gpio-i8255.h"
+
+#define I8255_CONTROL_PORTC_LOWER_DIRECTION BIT(0)
+#define I8255_CONTROL_PORTB_DIRECTION BIT(1)
+#define I8255_CONTROL_PORTC_UPPER_DIRECTION BIT(3)
+#define I8255_CONTROL_PORTA_DIRECTION BIT(4)
+#define I8255_CONTROL_MODE_SET BIT(7)
+#define I8255_PORTA 0
+#define I8255_PORTB 1
+#define I8255_PORTC 2
+
+static int i8255_get_port(struct i8255 __iomem *const ppi,
+			  const unsigned long io_port, const unsigned long mask)
+{
+	const unsigned long bank = io_port / 3;
+	const unsigned long ppi_port = io_port % 3;
+
+	return ioread8(&ppi[bank].port[ppi_port]) & mask;
+}
+
+static u8 i8255_direction_mask(const unsigned long offset)
+{
+	const unsigned long port_offset = offset % 8;
+	const unsigned long io_port = offset / 8;
+	const unsigned long ppi_port = io_port % 3;
+
+	switch (ppi_port) {
+	case I8255_PORTA:
+		return I8255_CONTROL_PORTA_DIRECTION;
+	case I8255_PORTB:
+		return I8255_CONTROL_PORTB_DIRECTION;
+	case I8255_PORTC:
+		/* Port C can be configured by nibble */
+		if (port_offset >= 4)
+			return I8255_CONTROL_PORTC_UPPER_DIRECTION;
+		return I8255_CONTROL_PORTC_LOWER_DIRECTION;
+	default:
+		/* Should never reach this path */
+		return 0;
+	}
+}
+
+static void i8255_set_port(struct i8255 __iomem *const ppi,
+			   struct i8255_state *const state,
+			   const unsigned long io_port,
+			   const unsigned long mask, const unsigned long bits)
+{
+	const unsigned long bank = io_port / 3;
+	const unsigned long ppi_port = io_port % 3;
+	unsigned long flags;
+	unsigned long out_state;
+
+	spin_lock_irqsave(&state[bank].lock, flags);
+
+	out_state = ioread8(&ppi[bank].port[ppi_port]);
+	out_state = (out_state & ~mask) | (bits & mask);
+	iowrite8(out_state, &ppi[bank].port[ppi_port]);
+
+	spin_unlock_irqrestore(&state[bank].lock, flags);
+}
+
+/**
+ * i8255_direction_input - configure signal offset as input
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @state:	devices states of the respective PPI banks
+ * @offset:	signal offset to configure as input
+ *
+ * Configures a signal @offset as input for the respective Intel 8255
+ * Programmable Peripheral Interface (@ppi) banks. The @state control_state
+ * values are updated to reflect the new configuration.
+ */
+void i8255_direction_input(struct i8255 __iomem *const ppi,
+			   struct i8255_state *const state,
+			   const unsigned long offset)
+{
+	const unsigned long io_port = offset / 8;
+	const unsigned long bank = io_port / 3;
+	unsigned long flags;
+
+	spin_lock_irqsave(&state[bank].lock, flags);
+
+	state[bank].control_state |= I8255_CONTROL_MODE_SET;
+	state[bank].control_state |= i8255_direction_mask(offset);
+
+	iowrite8(state[bank].control_state, &ppi[bank].control);
+
+	spin_unlock_irqrestore(&state[bank].lock, flags);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_direction_input, I8255);
+
+/**
+ * i8255_direction_output - configure signal offset as output
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @state:	devices states of the respective PPI banks
+ * @offset:	signal offset to configure as output
+ * @value:	signal value to output
+ *
+ * Configures a signal @offset as output for the respective Intel 8255
+ * Programmable Peripheral Interface (@ppi) banks and sets the respective signal
+ * output to the desired @value. The @state control_state values are updated to
+ * reflect the new configuration.
+ */
+void i8255_direction_output(struct i8255 __iomem *const ppi,
+			    struct i8255_state *const state,
+			    const unsigned long offset,
+			    const unsigned long value)
+{
+	const unsigned long io_port = offset / 8;
+	const unsigned long bank = io_port / 3;
+	unsigned long flags;
+
+	spin_lock_irqsave(&state[bank].lock, flags);
+
+	state[bank].control_state |= I8255_CONTROL_MODE_SET;
+	state[bank].control_state &= ~i8255_direction_mask(offset);
+
+	iowrite8(state[bank].control_state, &ppi[bank].control);
+
+	spin_unlock_irqrestore(&state[bank].lock, flags);
+
+	i8255_set(ppi, state, offset, value);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_direction_output, I8255);
+
+/**
+ * i8255_get - get signal value at signal offset
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @offset:	offset of signal to get
+ *
+ * Returns the signal value (0=low, 1=high) for the signal at @offset for the
+ * respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
+ */
+int i8255_get(struct i8255 __iomem *const ppi, const unsigned long offset)
+{
+	const unsigned long io_port = offset / 8;
+	const unsigned long offset_mask = BIT(offset % 8);
+
+	return !!i8255_get_port(ppi, io_port, offset_mask);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_get, I8255);
+
+/**
+ * i8255_get_direction - get the I/O direction for a signal offset
+ * @state:	devices states of the respective PPI banks
+ * @offset:	offset of signal to get direction
+ *
+ * Returns the signal direction (0=output, 1=input) for the signal at @offset.
+ */
+int i8255_get_direction(const struct i8255_state *const state,
+			const unsigned long offset)
+{
+	const unsigned long io_port = offset / 8;
+	const unsigned long bank = io_port / 3;
+
+	return !!(state[bank].control_state & i8255_direction_mask(offset));
+}
+EXPORT_SYMBOL_NS_GPL(i8255_get_direction, I8255);
+
+/**
+ * i8255_get_multiple - get multiple signal values at multiple signal offsets
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @mask:	mask of signals to get
+ * @bits:	bitmap to store signal values
+ * @ngpio:	number of GPIO signals of the respective PPI banks
+ *
+ * Stores in @bits the values (0=low, 1=high) for the signals defined by @mask
+ * for the respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
+ */
+void i8255_get_multiple(struct i8255 __iomem *const ppi,
+			const unsigned long *const mask,
+			unsigned long *const bits, const unsigned long ngpio)
+{
+	unsigned long offset;
+	unsigned long port_mask;
+	unsigned long io_port;
+	unsigned long port_state;
+
+	bitmap_zero(bits, ngpio);
+
+	for_each_set_clump8(offset, port_mask, mask, ngpio) {
+		io_port = offset / 8;
+		port_state = i8255_get_port(ppi, io_port, port_mask);
+
+		bitmap_set_value8(bits, port_state, offset);
+	}
+}
+EXPORT_SYMBOL_NS_GPL(i8255_get_multiple, I8255);
+
+/**
+ * i8255_mode0_output - configure all PPI ports to MODE 0 output mode
+ * @ppi:	Intel 8255 Programmable Peripheral Interface bank
+ *
+ * Configures all Intel 8255 Programmable Peripheral Interface (@ppi) ports to
+ * MODE 0 (Basic Input/Output) output mode.
+ */
+void i8255_mode0_output(struct i8255 __iomem *const ppi)
+{
+	iowrite8(I8255_CONTROL_MODE_SET, &ppi->control);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_mode0_output, I8255);
+
+/**
+ * i8255_set - set signal value at signal offset
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @state:	devices states of the respective PPI banks
+ * @offset:	offset of signal to set
+ * @value:	value of signal to set
+ *
+ * Assigns output @value for the signal at @offset for the respective Intel 8255
+ * Programmable Peripheral Interface (@ppi) banks.
+ */
+void i8255_set(struct i8255 __iomem *const ppi, struct i8255_state *const state,
+	       const unsigned long offset, const unsigned long value)
+{
+	const unsigned long io_port = offset / 8;
+	const unsigned long port_offset = offset % 8;
+	const unsigned long mask = BIT(port_offset);
+	const unsigned long bits = value << port_offset;
+
+	i8255_set_port(ppi, state, io_port, mask, bits);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_set, I8255);
+
+/**
+ * i8255_set_multiple - set signal values at multiple signal offsets
+ * @ppi:	Intel 8255 Programmable Peripheral Interface banks
+ * @state:	devices states of the respective PPI banks
+ * @mask:	mask of signals to set
+ * @bits:	bitmap of signal output values
+ * @ngpio:	number of GPIO signals of the respective PPI banks
+ *
+ * Assigns output values defined by @bits for the signals defined by @mask for
+ * the respective Intel 8255 Programmable Peripheral Interface (@ppi) banks.
+ */
+void i8255_set_multiple(struct i8255 __iomem *const ppi,
+			struct i8255_state *const state,
+			const unsigned long *const mask,
+			const unsigned long *const bits,
+			const unsigned long ngpio)
+{
+	unsigned long offset;
+	unsigned long port_mask;
+	unsigned long io_port;
+	unsigned long value;
+
+	for_each_set_clump8(offset, port_mask, mask, ngpio) {
+		io_port = offset / 8;
+		value = bitmap_get_value8(bits, offset);
+		i8255_set_port(ppi, state, io_port, port_mask, value);
+	}
+}
+EXPORT_SYMBOL_NS_GPL(i8255_set_multiple, I8255);
+
+/**
+ * i8255_state_init - initialize i8255_state structure
+ * @state:	devices states of the respective PPI banks
+ * @nbanks:	number of Intel 8255 Programmable Peripheral Interface banks
+ *
+ * Initializes the @state of each Intel 8255 Programmable Peripheral Interface
+ * bank for use in i8255 library functions.
+ */
+void i8255_state_init(struct i8255_state *const state,
+		      const unsigned long nbanks)
+{
+	unsigned long bank;
+
+	for (bank = 0; bank < nbanks; bank++)
+		spin_lock_init(&state[bank].lock);
+}
+EXPORT_SYMBOL_NS_GPL(i8255_state_init, I8255);
+
+MODULE_AUTHOR("William Breathitt Gray");
+MODULE_DESCRIPTION("Intel 8255 Programmable Peripheral Interface");
+MODULE_LICENSE("GPL");