staging: gpib: Add Fluke cda based cards GPIB driver

Driver for Fluke cda based cards

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20240918121908.19366-13-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gpib/eastwood/Makefile

@@ -0,0 +1,3 @@
+
+obj-m += fluke_gpib.o
+

drivers/staging/gpib/eastwood/fluke_gpib.h

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+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ *   Author: Frank Mori Hess <fmh6jj@gmail.com>
+ *   copyright: (C) 2006, 2010, 2015 Fluke Corporation
+ ***************************************************************************/
+
+#include <linux/compiler.h>
+#include <linux/dmaengine.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include "nec7210.h"
+
+struct fluke_priv {
+	struct nec7210_priv nec7210_priv;
+	struct resource *gpib_iomem_res;
+	struct resource *write_transfer_counter_res;
+	struct resource *dma_port_res;
+	int irq;
+	struct dma_chan *dma_channel;
+	u8 *dma_buffer;
+	int dma_buffer_size;
+	void *write_transfer_counter;
+};
+
+// cb7210 specific registers and bits
+enum cb7210_regs {
+	STATE1_REG = 0x4,
+	ISR0_IMR0 = 0x6,
+	BUS_STATUS = 0x7
+};
+
+enum cb7210_page_in {
+	ISR0_IMR0_PAGE = 1,
+	BUS_STATUS_PAGE = 1,
+	STATE1_PAGE = 1
+};
+
+/* IMR0 -- Interrupt Mode Register 0 */
+enum imr0_bits {
+	FLUKE_IFCIE_BIT = 0x8,	/* interface clear interrupt */
+};
+
+/* ISR0 -- Interrupt Status Register 0 */
+enum isr0_bits {
+	FLUKE_IFCI_BIT = 0x8,	/* interface clear interrupt */
+};
+
+enum state1_bits {
+	SOURCE_HANDSHAKE_SIDS_BITS = 0x0, /* source idle state */
+	SOURCE_HANDSHAKE_SGNS_BITS = 0x1, /* source generate state */
+	SOURCE_HANDSHAKE_SDYS_BITS = 0x2, /* source delay state */
+	SOURCE_HANDSHAKE_STRS_BITS = 0x5, /* source transfer state */
+	SOURCE_HANDSHAKE_MASK = 0x7
+};
+
+// we customized the cb7210 vhdl to give the "data in" status
+// on the unused bit 7 of the address0 register.
+enum cb7210_address0 {
+	DATA_IN_STATUS = 0x80
+};
+
+static inline int cb7210_page_in_bits(unsigned int page)
+{
+	return 0x50 | (page & 0xf);
+}
+
+// don't use without locking nec_priv->register_page_lock
+static inline uint8_t fluke_read_byte_nolock(struct nec7210_priv *nec_priv,
+					     int register_num)
+{
+	u8 retval;
+
+	retval = readl(nec_priv->iobase + register_num * nec_priv->offset);
+	return retval;
+}
+
+// don't use without locking nec_priv->register_page_lock
+static inline void fluke_write_byte_nolock(struct nec7210_priv *nec_priv, uint8_t data,
+					   int register_num)
+{
+	writel(data, nec_priv->iobase + register_num * nec_priv->offset);
+}
+
+static inline uint8_t fluke_paged_read_byte(struct fluke_priv *e_priv,
+					    unsigned int register_num, unsigned int page)
+{
+	struct nec7210_priv *nec_priv = &e_priv->nec7210_priv;
+	u8 retval;
+	unsigned long flags;
+
+	spin_lock_irqsave(&nec_priv->register_page_lock, flags);
+	fluke_write_byte_nolock(nec_priv, cb7210_page_in_bits(page), AUXMR);
+	udelay(1);
+	/* chip auto clears the page after a read */
+	retval = fluke_read_byte_nolock(nec_priv, register_num);
+	spin_unlock_irqrestore(&nec_priv->register_page_lock, flags);
+	return retval;
+}
+
+static inline void fluke_paged_write_byte(struct fluke_priv *e_priv, uint8_t data,
+					  unsigned int register_num, unsigned int page)
+{
+	struct nec7210_priv *nec_priv = &e_priv->nec7210_priv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&nec_priv->register_page_lock, flags);
+	fluke_write_byte_nolock(nec_priv, cb7210_page_in_bits(page), AUXMR);
+	udelay(1);
+	fluke_write_byte_nolock(nec_priv, data, register_num);
+	spin_unlock_irqrestore(&nec_priv->register_page_lock, flags);
+}
+
+enum bus_status_bits {
+	BSR_ATN_BIT = 0x1,
+	BSR_EOI_BIT = 0x2,
+	BSR_SRQ_BIT = 0x4,
+	BSR_IFC_BIT = 0x8,
+	BSR_REN_BIT = 0x10,
+	BSR_DAV_BIT = 0x20,
+	BSR_NRFD_BIT = 0x40,
+	BSR_NDAC_BIT = 0x80,
+};
+
+enum cb7210_aux_cmds {
+/* AUX_RTL2 is an undocumented aux command which causes cb7210 to assert
+ *	(and keep asserted) local rtl message.  This is used in conjunction
+ *	with the (stupid) cb7210 implementation
+ *	of the normal nec7210 AUX_RTL aux command, which
+ *	causes the rtl message to toggle between on and off.
+ */
+	AUX_RTL2 = 0xd,
+	AUX_NBAF = 0xe,	// new byte available false (also clears seoi)
+	AUX_LO_SPEED = 0x40,
+	AUX_HI_SPEED = 0x41,
+};
+
+static const int fluke_reg_offset = 4;
+static const int fluke_num_regs = 8;
+static const unsigned int write_transfer_counter_mask = 0x7ff;