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Date:   Thu, 14 May 2020 02:07:46 +0200
From:   Marek Vasut <marex@...x.de>
To:     netdev@...r.kernel.org
Cc:     Marek Vasut <marex@...x.de>,
        "David S . Miller" <davem@...emloft.net>,
        Lukas Wunner <lukas@...ner.de>, Petr Stetiar <ynezz@...e.cz>,
        YueHaibing <yuehaibing@...wei.com>
Subject: [PATCH V5 18/19] net: ks8851: Implement Parallel bus operations

Implement accessors for KS8851-16MLL/MLLI/MLLU parallel bus variant of
the KS8851. This is based off the ks8851_mll.c , which is a driver for
exactly the same hardware, however the ks8851.c code is much higher
quality. Hence, this patch pulls out the relevant information from the
ks8851_mll.c on how to access the bus, but uses the common ks8851.c
code. To make this patch reviewable, instead of rewriting ks8851_mll.c,
ks8851_mll.c is removed in a separate subsequent patch.

Signed-off-by: Marek Vasut <marex@...x.de>
Cc: David S. Miller <davem@...emloft.net>
Cc: Lukas Wunner <lukas@...ner.de>
Cc: Petr Stetiar <ynezz@...e.cz>
Cc: YueHaibing <yuehaibing@...wei.com>
---
V2: - Drop 'must be first' comment on the embedded struct ks8851_net
    - Add missing Kconfig 'select's to match the KS8851 SPI driver
    - Get rid of the pointer indirection
    - Repair the endian handling and add endian check
V3: - Adjust Makefile to permit build as a module
    - Enable only RX and LCx interrupts
V4: No change
V5: - Move msg_enable module param to ks8851_par.c
---
 drivers/net/ethernet/micrel/Kconfig      |   2 +
 drivers/net/ethernet/micrel/Makefile     |   1 +
 drivers/net/ethernet/micrel/ks8851_par.c | 348 +++++++++++++++++++++++
 3 files changed, 351 insertions(+)
 create mode 100644 drivers/net/ethernet/micrel/ks8851_par.c

diff --git a/drivers/net/ethernet/micrel/Kconfig b/drivers/net/ethernet/micrel/Kconfig
index b9c4d48e28e4..09f35209d43d 100644
--- a/drivers/net/ethernet/micrel/Kconfig
+++ b/drivers/net/ethernet/micrel/Kconfig
@@ -38,6 +38,8 @@ config KS8851_MLL
 	tristate "Micrel KS8851 MLL"
 	depends on HAS_IOMEM
 	select MII
+	select CRC32
+	select EEPROM_93CX6
 	---help---
 	  This platform driver is for Micrel KS8851 Address/data bus
 	  multiplexed network chip.
diff --git a/drivers/net/ethernet/micrel/Makefile b/drivers/net/ethernet/micrel/Makefile
index c7a4725c2e95..5cc00d22c708 100644
--- a/drivers/net/ethernet/micrel/Makefile
+++ b/drivers/net/ethernet/micrel/Makefile
@@ -7,4 +7,5 @@ obj-$(CONFIG_KS8842) += ks8842.o
 obj-$(CONFIG_KS8851) += ks8851.o
 ks8851-objs = ks8851_common.o ks8851_spi.o
 obj-$(CONFIG_KS8851_MLL) += ks8851_mll.o
+ks8851_mll-objs = ks8851_common.o ks8851_par.o
 obj-$(CONFIG_KSZ884X_PCI) += ksz884x.o
diff --git a/drivers/net/ethernet/micrel/ks8851_par.c b/drivers/net/ethernet/micrel/ks8851_par.c
new file mode 100644
index 000000000000..90fffacb1695
--- /dev/null
+++ b/drivers/net/ethernet/micrel/ks8851_par.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* drivers/net/ethernet/micrel/ks8851.c
+ *
+ * Copyright 2009 Simtec Electronics
+ *	http://www.simtec.co.uk/
+ *	Ben Dooks <ben@...tec.co.uk>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#define DEBUG
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/cache.h>
+#include <linux/crc32.h>
+#include <linux/mii.h>
+#include <linux/regulator/consumer.h>
+
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/of_net.h>
+
+#include "ks8851.h"
+
+static int msg_enable;
+
+#define BE3             0x8000      /* Byte Enable 3 */
+#define BE2             0x4000      /* Byte Enable 2 */
+#define BE1             0x2000      /* Byte Enable 1 */
+#define BE0             0x1000      /* Byte Enable 0 */
+
+/**
+ * struct ks8851_net_par - KS8851 Parallel driver private data
+ * @ks8851: KS8851 driver common private data
+ * @lock: Lock to ensure that the device is not accessed when busy.
+ * @hw_addr	: start address of data register.
+ * @hw_addr_cmd	: start address of command register.
+ * @cmd_reg_cache	: command register cached.
+ *
+ * The @lock ensures that the chip is protected when certain operations are
+ * in progress. When the read or write packet transfer is in progress, most
+ * of the chip registers are not ccessible until the transfer is finished and
+ * the DMA has been de-asserted.
+ */
+struct ks8851_net_par {
+	struct ks8851_net	ks8851;
+	spinlock_t		lock;
+	void __iomem		*hw_addr;
+	void __iomem		*hw_addr_cmd;
+	u16			cmd_reg_cache;
+};
+
+#define to_ks8851_par(ks) container_of((ks), struct ks8851_net_par, ks8851)
+
+/**
+ * ks8851_lock_par - register access lock
+ * @ks: The chip state
+ * @flags: Spinlock flags
+ *
+ * Claim chip register access lock
+ */
+static void ks8851_lock_par(struct ks8851_net *ks, unsigned long *flags)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+
+	spin_lock_irqsave(&ksp->lock, *flags);
+}
+
+/**
+ * ks8851_unlock_par - register access unlock
+ * @ks: The chip state
+ * @flags: Spinlock flags
+ *
+ * Release chip register access lock
+ */
+static void ks8851_unlock_par(struct ks8851_net *ks, unsigned long *flags)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+
+	spin_unlock_irqrestore(&ksp->lock, *flags);
+}
+
+/**
+ * ks_check_endian - Check whether endianness of the bus is correct
+ * @ks	  : The chip information
+ *
+ * The KS8851-16MLL EESK pin allows selecting the endianness of the 16bit
+ * bus. To maintain optimum performance, the bus endianness should be set
+ * such that it matches the endianness of the CPU.
+ */
+static int ks_check_endian(struct ks8851_net *ks)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+	u16 cider;
+
+	/*
+	 * Read CIDER register first, however read it the "wrong" way around.
+	 * If the endian strap on the KS8851-16MLL in incorrect and the chip
+	 * is operating in different endianness than the CPU, then the meaning
+	 * of BE[3:0] byte-enable bits is also swapped such that:
+	 *    BE[3,2,1,0] becomes BE[1,0,3,2]
+	 *
+	 * Luckily for us, the byte-enable bits are the top four MSbits of
+	 * the address register and the CIDER register is at offset 0xc0.
+	 * Hence, by reading address 0xc0c0, which is not impacted by endian
+	 * swapping, we assert either BE[3:2] or BE[1:0] while reading the
+	 * CIDER register.
+	 *
+	 * If the bus configuration is correct, reading 0xc0c0 asserts
+	 * BE[3:2] and this read returns 0x0000, because to read register
+	 * with bottom two LSbits of address set to 0, BE[1:0] must be
+	 * asserted.
+	 *
+	 * If the bus configuration is NOT correct, reading 0xc0c0 asserts
+	 * BE[1:0] and this read returns non-zero 0x8872 value.
+	 */
+	iowrite16(BE3 | BE2 | KS_CIDER, ksp->hw_addr_cmd);
+	cider = ioread16(ksp->hw_addr);
+	if (!cider)
+		return 0;
+
+	netdev_err(ks->netdev, "incorrect EESK endian strap setting\n");
+
+	return -EINVAL;
+}
+
+/**
+ * ks8851_wrreg16_par - write 16bit register value to chip
+ * @ks: The chip state
+ * @reg: The register address
+ * @val: The value to write
+ *
+ * Issue a write to put the value @val into the register specified in @reg.
+ */
+static void ks8851_wrreg16_par(struct ks8851_net *ks, unsigned int reg,
+			       unsigned int val)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+
+	ksp->cmd_reg_cache = (u16)reg | ((BE1 | BE0) << (reg & 0x02));
+	iowrite16(ksp->cmd_reg_cache, ksp->hw_addr_cmd);
+	iowrite16(val, ksp->hw_addr);
+}
+
+/**
+ * ks8851_rdreg16_par - read 16 bit register from chip
+ * @ks: The chip information
+ * @reg: The register address
+ *
+ * Read a 16bit register from the chip, returning the result
+ */
+static unsigned int ks8851_rdreg16_par(struct ks8851_net *ks, unsigned int reg)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+
+	ksp->cmd_reg_cache = (u16)reg | ((BE1 | BE0) << (reg & 0x02));
+	iowrite16(ksp->cmd_reg_cache, ksp->hw_addr_cmd);
+	return ioread16(ksp->hw_addr);
+}
+
+/**
+ * ks8851_rdfifo_par - read data from the receive fifo
+ * @ks: The device state.
+ * @buff: The buffer address
+ * @len: The length of the data to read
+ *
+ * Issue an RXQ FIFO read command and read the @len amount of data from
+ * the FIFO into the buffer specified by @buff.
+ */
+static void ks8851_rdfifo_par(struct ks8851_net *ks, u8 *buff, unsigned int len)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+
+	netif_dbg(ks, rx_status, ks->netdev,
+		  "%s: %d@%p\n", __func__, len, buff);
+
+	ioread16_rep(ksp->hw_addr, (u16 *)buff + 1, len / 2);
+}
+
+/**
+ * ks8851_wrfifo_par - write packet to TX FIFO
+ * @ks: The device state.
+ * @txp: The sk_buff to transmit.
+ * @irq: IRQ on completion of the packet.
+ *
+ * Send the @txp to the chip. This means creating the relevant packet header
+ * specifying the length of the packet and the other information the chip
+ * needs, such as IRQ on completion. Send the header and the packet data to
+ * the device.
+ */
+static void ks8851_wrfifo_par(struct ks8851_net *ks, struct sk_buff *txp,
+			      bool irq)
+{
+	struct ks8851_net_par *ksp = to_ks8851_par(ks);
+	unsigned int len = ALIGN(txp->len, 4);
+	unsigned int fid = 0;
+
+	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
+		  __func__, txp, txp->len, txp->data, irq);
+
+	fid = ks->fid++;
+	fid &= TXFR_TXFID_MASK;
+
+	if (irq)
+		fid |= TXFR_TXIC;	/* irq on completion */
+
+	iowrite16(fid, ksp->hw_addr);
+	iowrite16(txp->len, ksp->hw_addr);
+
+	iowrite16_rep(ksp->hw_addr, txp->data, len / 2);
+}
+
+/**
+ * ks8851_rx_skb_par - receive skbuff
+ * @skb: The skbuff
+ */
+static void ks8851_rx_skb_par(struct ks8851_net *ks, struct sk_buff *skb)
+{
+	netif_rx(skb);
+}
+
+/**
+ * ks8851_start_xmit_par - transmit packet
+ * @skb: The buffer to transmit
+ * @dev: The device used to transmit the packet.
+ *
+ * Called by the network layer to transmit the @skb. Queue the packet for
+ * the device and schedule the necessary work to transmit the packet when
+ * it is free.
+ *
+ * We do this to firstly avoid sleeping with the network device locked,
+ * and secondly so we can round up more than one packet to transmit which
+ * means we can try and avoid generating too many transmit done interrupts.
+ */
+static netdev_tx_t ks8851_start_xmit_par(struct sk_buff *skb,
+					 struct net_device *dev)
+{
+	struct ks8851_net *ks = netdev_priv(dev);
+	netdev_tx_t ret = NETDEV_TX_OK;
+	unsigned long flags;
+	u16 txmir;
+
+	netif_dbg(ks, tx_queued, ks->netdev,
+		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);
+
+	ks8851_lock_par(ks, &flags);
+
+	txmir = ks8851_rdreg16_par(ks, KS_TXMIR) & 0x1fff;
+
+	if (likely(txmir >= skb->len + 12)) {
+		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);
+		ks8851_wrfifo_par(ks, skb, false);
+		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr);
+		ks8851_wrreg16_par(ks, KS_TXQCR, TXQCR_METFE);
+		while (ks8851_rdreg16_par(ks, KS_TXQCR) & TXQCR_METFE)
+			;
+		ks8851_done_tx(ks, skb);
+	} else {
+		ret = NETDEV_TX_BUSY;
+	}
+
+	ks8851_unlock_par(ks, &flags);
+
+	return ret;
+}
+
+static int ks8851_probe_par(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ks8851_net_par *ksp;
+	struct net_device *netdev;
+	struct ks8851_net *ks;
+	int ret;
+
+	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_par));
+	if (!netdev)
+		return -ENOMEM;
+
+	ks = netdev_priv(netdev);
+
+	ks->lock = ks8851_lock_par;
+	ks->unlock = ks8851_unlock_par;
+	ks->rdreg16 = ks8851_rdreg16_par;
+	ks->wrreg16 = ks8851_wrreg16_par;
+	ks->rdfifo = ks8851_rdfifo_par;
+	ks->wrfifo = ks8851_wrfifo_par;
+	ks->start_xmit = ks8851_start_xmit_par;
+	ks->rx_skb = ks8851_rx_skb_par;
+
+#define STD_IRQ (IRQ_LCI |	/* Link Change */	\
+		 IRQ_RXI |	/* RX done */		\
+		 IRQ_RXPSI)	/* RX process stop */
+	ks->rc_ier = STD_IRQ;
+
+	ksp = to_ks8851_par(ks);
+	spin_lock_init(&ksp->lock);
+
+	ksp->hw_addr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ksp->hw_addr))
+		return PTR_ERR(ksp->hw_addr);
+
+	ksp->hw_addr_cmd = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(ksp->hw_addr_cmd))
+		return PTR_ERR(ksp->hw_addr_cmd);
+
+	ret = ks_check_endian(ks);
+	if (ret)
+		return ret;
+
+	netdev->irq = platform_get_irq(pdev, 0);
+
+	return ks8851_probe_common(netdev, dev, msg_enable);
+}
+
+static int ks8851_remove_par(struct platform_device *pdev)
+{
+	return ks8851_remove_common(&pdev->dev);
+}
+
+static const struct of_device_id ks8851_match_table[] = {
+	{ .compatible = "micrel,ks8851-mll" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ks8851_match_table);
+
+static struct platform_driver ks8851_driver = {
+	.driver = {
+		.name = "ks8851",
+		.of_match_table = ks8851_match_table,
+		.pm = &ks8851_pm_ops,
+	},
+	.probe = ks8851_probe_par,
+	.remove = ks8851_remove_par,
+};
+module_platform_driver(ks8851_driver);
+
+MODULE_DESCRIPTION("KS8851 Network driver");
+MODULE_AUTHOR("Ben Dooks <ben@...tec.co.uk>");
+MODULE_LICENSE("GPL");
+
+module_param_named(message, msg_enable, int, 0);
+MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
-- 
2.25.1

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