gpio: idio-16: Introduce the ACCES IDIO-16 GPIO library module

Exposes consumer library functions to facilitate communication with
devices within the ACCES IDIO-16 family such as the 104-IDIO-16 and
the PCI-IDIO-16.

A CONFIG_GPIO_IDIO_16 Kconfig option is introduced by this patch.
Modules wanting access to these idio-16 library functions should select
this Kconfig option and import the GPIO_IDIO_16 symbol namespace.

Cc: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

1 files changed, 146 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-idio-16.c b/drivers/gpio/gpio-idio-16.c
new file mode 100644
index 000000000000..13315242d220
--- /dev/null
+++ b/drivers/gpio/gpio-idio-16.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO library for the ACCES IDIO-16 family
+ * Copyright (C) 2022 William Breathitt Gray
+ */
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "gpio-idio-16.h"
+
+#define DEFAULT_SYMBOL_NAMESPACE GPIO_IDIO_16
+
+/**
+ * idio_16_get - get signal value at signal offset
+ * @reg:	ACCES IDIO-16 device registers
+ * @state:	ACCES IDIO-16 device state
+ * @offset:	offset of signal to get
+ *
+ * Returns the signal value (0=low, 1=high) for the signal at @offset.
+ */
+int idio_16_get(struct idio_16 __iomem *const reg,
+		struct idio_16_state *const state, const unsigned long offset)
+{
+	const unsigned long mask = BIT(offset);
+
+	if (offset < IDIO_16_NOUT)
+		return test_bit(offset, state->out_state);
+
+	if (offset < 24)
+		return !!(ioread8(&reg->in0_7) & (mask >> IDIO_16_NOUT));
+
+	if (offset < 32)
+		return !!(ioread8(&reg->in8_15) & (mask >> 24));
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(idio_16_get);
+
+/**
+ * idio_16_get_multiple - get multiple signal values at multiple signal offsets
+ * @reg:	ACCES IDIO-16 device registers
+ * @state:	ACCES IDIO-16 device state
+ * @mask:	mask of signals to get
+ * @bits:	bitmap to store signal values
+ *
+ * Stores in @bits the values (0=low, 1=high) for the signals defined by @mask.
+ */
+void idio_16_get_multiple(struct idio_16 __iomem *const reg,
+			  struct idio_16_state *const state,
+			  const unsigned long *const mask,
+			  unsigned long *const bits)
+{
+	unsigned long flags;
+	const unsigned long out_mask = GENMASK(IDIO_16_NOUT - 1, 0);
+
+	spin_lock_irqsave(&state->lock, flags);
+
+	bitmap_replace(bits, bits, state->out_state, &out_mask, IDIO_16_NOUT);
+	if (*mask & GENMASK(23, 16))
+		bitmap_set_value8(bits, ioread8(&reg->in0_7), 16);
+	if (*mask & GENMASK(31, 24))
+		bitmap_set_value8(bits, ioread8(&reg->in8_15), 24);
+
+	spin_unlock_irqrestore(&state->lock, flags);
+}
+EXPORT_SYMBOL_GPL(idio_16_get_multiple);
+
+/**
+ * idio_16_set - set signal value at signal offset
+ * @reg:	ACCES IDIO-16 device registers
+ * @state:	ACCES IDIO-16 device state
+ * @offset:	offset of signal to set
+ * @value:	value of signal to set
+ *
+ * Assigns output @value for the signal at @offset.
+ */
+void idio_16_set(struct idio_16 __iomem *const reg,
+		 struct idio_16_state *const state, const unsigned long offset,
+		 const unsigned long value)
+{
+	unsigned long flags;
+
+	if (offset >= IDIO_16_NOUT)
+		return;
+
+	spin_lock_irqsave(&state->lock, flags);
+
+	__assign_bit(offset, state->out_state, value);
+	if (offset < 8)
+		iowrite8(bitmap_get_value8(state->out_state, 0), &reg->out0_7);
+	else
+		iowrite8(bitmap_get_value8(state->out_state, 8), &reg->out8_15);
+
+	spin_unlock_irqrestore(&state->lock, flags);
+}
+EXPORT_SYMBOL_GPL(idio_16_set);
+
+/**
+ * idio_16_set_multiple - set signal values at multiple signal offsets
+ * @reg:	ACCES IDIO-16 device registers
+ * @state:	ACCES IDIO-16 device state
+ * @mask:	mask of signals to set
+ * @bits:	bitmap of signal output values
+ *
+ * Assigns output values defined by @bits for the signals defined by @mask.
+ */
+void idio_16_set_multiple(struct idio_16 __iomem *const reg,
+			  struct idio_16_state *const state,
+			  const unsigned long *const mask,
+			  const unsigned long *const bits)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&state->lock, flags);
+
+	bitmap_replace(state->out_state, state->out_state, bits, mask,
+		       IDIO_16_NOUT);
+	if (*mask & GENMASK(7, 0))
+		iowrite8(bitmap_get_value8(state->out_state, 0), &reg->out0_7);
+	if (*mask & GENMASK(15, 8))
+		iowrite8(bitmap_get_value8(state->out_state, 8), &reg->out8_15);
+
+	spin_unlock_irqrestore(&state->lock, flags);
+}
+EXPORT_SYMBOL_GPL(idio_16_set_multiple);
+
+/**
+ * idio_16_state_init - initialize idio_16_state structure
+ * @state:	ACCES IDIO-16 device state
+ *
+ * Initializes the ACCES IDIO-16 device @state for use in idio-16 library
+ * functions.
+ */
+void idio_16_state_init(struct idio_16_state *const state)
+{
+	spin_lock_init(&state->lock);
+}
+EXPORT_SYMBOL_GPL(idio_16_state_init);
+
+MODULE_AUTHOR("William Breathitt Gray");
+MODULE_DESCRIPTION("ACCES IDIO-16 GPIO Library");
+MODULE_LICENSE("GPL");