1// SPDX-License-Identifier: GPL-2.0-only
2/* drivers/net/ethernet/micrel/ks8851.c
3 *
4 * Copyright 2009 Simtec Electronics
5 *	http://www.simtec.co.uk/
6 *	Ben Dooks <ben@simtec.co.uk>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/interrupt.h>
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/netdevice.h>
15#include <linux/etherdevice.h>
16#include <linux/ethtool.h>
17#include <linux/iopoll.h>
18#include <linux/mii.h>
19
20#include <linux/platform_device.h>
21#include <linux/of_net.h>
22
23#include "ks8851.h"
24
25static int msg_enable;
26
27#define BE3             0x8000      /* Byte Enable 3 */
28#define BE2             0x4000      /* Byte Enable 2 */
29#define BE1             0x2000      /* Byte Enable 1 */
30#define BE0             0x1000      /* Byte Enable 0 */
31
32/**
33 * struct ks8851_net_par - KS8851 Parallel driver private data
34 * @ks8851: KS8851 driver common private data
35 * @lock: Lock to ensure that the device is not accessed when busy.
36 * @hw_addr	: start address of data register.
37 * @hw_addr_cmd	: start address of command register.
38 * @cmd_reg_cache	: command register cached.
39 *
40 * The @lock ensures that the chip is protected when certain operations are
41 * in progress. When the read or write packet transfer is in progress, most
42 * of the chip registers are not accessible until the transfer is finished
43 * and the DMA has been de-asserted.
44 */
45struct ks8851_net_par {
46	struct ks8851_net	ks8851;
47	spinlock_t		lock;
48	void __iomem		*hw_addr;
49	void __iomem		*hw_addr_cmd;
50	u16			cmd_reg_cache;
51};
52
53#define to_ks8851_par(ks) container_of((ks), struct ks8851_net_par, ks8851)
54
55/**
56 * ks8851_lock_par - register access lock
57 * @ks: The chip state
58 * @flags: Spinlock flags
59 *
60 * Claim chip register access lock
61 */
62static void ks8851_lock_par(struct ks8851_net *ks, unsigned long *flags)
63{
64	struct ks8851_net_par *ksp = to_ks8851_par(ks);
65
66	spin_lock_irqsave(&ksp->lock, *flags);
67}
68
69/**
70 * ks8851_unlock_par - register access unlock
71 * @ks: The chip state
72 * @flags: Spinlock flags
73 *
74 * Release chip register access lock
75 */
76static void ks8851_unlock_par(struct ks8851_net *ks, unsigned long *flags)
77{
78	struct ks8851_net_par *ksp = to_ks8851_par(ks);
79
80	spin_unlock_irqrestore(&ksp->lock, *flags);
81}
82
83/**
84 * ks_check_endian - Check whether endianness of the bus is correct
85 * @ks	  : The chip information
86 *
87 * The KS8851-16MLL EESK pin allows selecting the endianness of the 16bit
88 * bus. To maintain optimum performance, the bus endianness should be set
89 * such that it matches the endianness of the CPU.
90 */
91static int ks_check_endian(struct ks8851_net *ks)
92{
93	struct ks8851_net_par *ksp = to_ks8851_par(ks);
94	u16 cider;
95
96	/*
97	 * Read CIDER register first, however read it the "wrong" way around.
98	 * If the endian strap on the KS8851-16MLL in incorrect and the chip
99	 * is operating in different endianness than the CPU, then the meaning
100	 * of BE[3:0] byte-enable bits is also swapped such that:
101	 *    BE[3,2,1,0] becomes BE[1,0,3,2]
102	 *
103	 * Luckily for us, the byte-enable bits are the top four MSbits of
104	 * the address register and the CIDER register is at offset 0xc0.
105	 * Hence, by reading address 0xc0c0, which is not impacted by endian
106	 * swapping, we assert either BE[3:2] or BE[1:0] while reading the
107	 * CIDER register.
108	 *
109	 * If the bus configuration is correct, reading 0xc0c0 asserts
110	 * BE[3:2] and this read returns 0x0000, because to read register
111	 * with bottom two LSbits of address set to 0, BE[1:0] must be
112	 * asserted.
113	 *
114	 * If the bus configuration is NOT correct, reading 0xc0c0 asserts
115	 * BE[1:0] and this read returns non-zero 0x8872 value.
116	 */
117	iowrite16(BE3 | BE2 | KS_CIDER, ksp->hw_addr_cmd);
118	cider = ioread16(ksp->hw_addr);
119	if (!cider)
120		return 0;
121
122	netdev_err(ks->netdev, "incorrect EESK endian strap setting\n");
123
124	return -EINVAL;
125}
126
127/**
128 * ks8851_wrreg16_par - write 16bit register value to chip
129 * @ks: The chip state
130 * @reg: The register address
131 * @val: The value to write
132 *
133 * Issue a write to put the value @val into the register specified in @reg.
134 */
135static void ks8851_wrreg16_par(struct ks8851_net *ks, unsigned int reg,
136			       unsigned int val)
137{
138	struct ks8851_net_par *ksp = to_ks8851_par(ks);
139
140	ksp->cmd_reg_cache = (u16)reg | ((BE1 | BE0) << (reg & 0x02));
141	iowrite16(ksp->cmd_reg_cache, ksp->hw_addr_cmd);
142	iowrite16(val, ksp->hw_addr);
143}
144
145/**
146 * ks8851_rdreg16_par - read 16 bit register from chip
147 * @ks: The chip information
148 * @reg: The register address
149 *
150 * Read a 16bit register from the chip, returning the result
151 */
152static unsigned int ks8851_rdreg16_par(struct ks8851_net *ks, unsigned int reg)
153{
154	struct ks8851_net_par *ksp = to_ks8851_par(ks);
155
156	ksp->cmd_reg_cache = (u16)reg | ((BE1 | BE0) << (reg & 0x02));
157	iowrite16(ksp->cmd_reg_cache, ksp->hw_addr_cmd);
158	return ioread16(ksp->hw_addr);
159}
160
161/**
162 * ks8851_rdfifo_par - read data from the receive fifo
163 * @ks: The device state.
164 * @buff: The buffer address
165 * @len: The length of the data to read
166 *
167 * Issue an RXQ FIFO read command and read the @len amount of data from
168 * the FIFO into the buffer specified by @buff.
169 */
170static void ks8851_rdfifo_par(struct ks8851_net *ks, u8 *buff, unsigned int len)
171{
172	struct ks8851_net_par *ksp = to_ks8851_par(ks);
173
174	netif_dbg(ks, rx_status, ks->netdev,
175		  "%s: %d@%p\n", __func__, len, buff);
176
177	ioread16_rep(ksp->hw_addr, (u16 *)buff + 1, len / 2);
178}
179
180/**
181 * ks8851_wrfifo_par - write packet to TX FIFO
182 * @ks: The device state.
183 * @txp: The sk_buff to transmit.
184 * @irq: IRQ on completion of the packet.
185 *
186 * Send the @txp to the chip. This means creating the relevant packet header
187 * specifying the length of the packet and the other information the chip
188 * needs, such as IRQ on completion. Send the header and the packet data to
189 * the device.
190 */
191static void ks8851_wrfifo_par(struct ks8851_net *ks, struct sk_buff *txp,
192			      bool irq)
193{
194	struct ks8851_net_par *ksp = to_ks8851_par(ks);
195	unsigned int len = ALIGN(txp->len, 4);
196	unsigned int fid = 0;
197
198	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
199		  __func__, txp, txp->len, txp->data, irq);
200
201	fid = ks->fid++;
202	fid &= TXFR_TXFID_MASK;
203
204	if (irq)
205		fid |= TXFR_TXIC;	/* irq on completion */
206
207	iowrite16(fid, ksp->hw_addr);
208	iowrite16(txp->len, ksp->hw_addr);
209
210	iowrite16_rep(ksp->hw_addr, txp->data, len / 2);
211}
212
213static unsigned int ks8851_rdreg16_par_txqcr(struct ks8851_net *ks)
214{
215	return ks8851_rdreg16_par(ks, KS_TXQCR);
216}
217
218/**
219 * ks8851_start_xmit_par - transmit packet
220 * @skb: The buffer to transmit
221 * @dev: The device used to transmit the packet.
222 *
223 * Called by the network layer to transmit the @skb. Queue the packet for
224 * the device and schedule the necessary work to transmit the packet when
225 * it is free.
226 *
227 * We do this to firstly avoid sleeping with the network device locked,
228 * and secondly so we can round up more than one packet to transmit which
229 * means we can try and avoid generating too many transmit done interrupts.
230 */
231static netdev_tx_t ks8851_start_xmit_par(struct sk_buff *skb,
232					 struct net_device *dev)
233{
234	struct ks8851_net *ks = netdev_priv(dev);
235	netdev_tx_t ret = NETDEV_TX_OK;
236	unsigned long flags;
237	unsigned int txqcr;
238	u16 txmir;
239	int err;
240
241	netif_dbg(ks, tx_queued, ks->netdev,
242		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);
243
244	ks8851_lock_par(ks, &flags);
245
246	txmir = ks8851_rdreg16_par(ks, KS_TXMIR) & 0x1fff;
247
248	if (likely(txmir >= skb->len + 12)) {
249		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);
250		ks8851_wrfifo_par(ks, skb, false);
251		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr);
252		ks8851_wrreg16_par(ks, KS_TXQCR, TXQCR_METFE);
253
254		err = readx_poll_timeout_atomic(ks8851_rdreg16_par_txqcr, ks,
255						txqcr, !(txqcr & TXQCR_METFE),
256						5, 1000000);
257		if (err)
258			ret = NETDEV_TX_BUSY;
259
260		ks8851_done_tx(ks, skb);
261	} else {
262		ret = NETDEV_TX_BUSY;
263	}
264
265	ks8851_unlock_par(ks, &flags);
266
267	return ret;
268}
269
270static int ks8851_probe_par(struct platform_device *pdev)
271{
272	struct device *dev = &pdev->dev;
273	struct ks8851_net_par *ksp;
274	struct net_device *netdev;
275	struct ks8851_net *ks;
276	int ret;
277
278	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_par));
279	if (!netdev)
280		return -ENOMEM;
281
282	ks = netdev_priv(netdev);
283
284	ks->lock = ks8851_lock_par;
285	ks->unlock = ks8851_unlock_par;
286	ks->rdreg16 = ks8851_rdreg16_par;
287	ks->wrreg16 = ks8851_wrreg16_par;
288	ks->rdfifo = ks8851_rdfifo_par;
289	ks->wrfifo = ks8851_wrfifo_par;
290	ks->start_xmit = ks8851_start_xmit_par;
291
292#define STD_IRQ (IRQ_LCI |	/* Link Change */	\
293		 IRQ_RXI |	/* RX done */		\
294		 IRQ_RXPSI)	/* RX process stop */
295	ks->rc_ier = STD_IRQ;
296
297	ksp = to_ks8851_par(ks);
298	spin_lock_init(&ksp->lock);
299
300	ksp->hw_addr = devm_platform_ioremap_resource(pdev, 0);
301	if (IS_ERR(ksp->hw_addr))
302		return PTR_ERR(ksp->hw_addr);
303
304	ksp->hw_addr_cmd = devm_platform_ioremap_resource(pdev, 1);
305	if (IS_ERR(ksp->hw_addr_cmd))
306		return PTR_ERR(ksp->hw_addr_cmd);
307
308	ret = ks_check_endian(ks);
309	if (ret)
310		return ret;
311
312	netdev->irq = platform_get_irq(pdev, 0);
313	if (netdev->irq < 0)
314		return netdev->irq;
315
316	return ks8851_probe_common(netdev, dev, msg_enable);
317}
318
319static void ks8851_remove_par(struct platform_device *pdev)
320{
321	ks8851_remove_common(&pdev->dev);
322}
323
324static const struct of_device_id ks8851_match_table[] = {
325	{ .compatible = "micrel,ks8851-mll" },
326	{ }
327};
328MODULE_DEVICE_TABLE(of, ks8851_match_table);
329
330static struct platform_driver ks8851_driver = {
331	.driver = {
332		.name = "ks8851",
333		.of_match_table = ks8851_match_table,
334		.pm = &ks8851_pm_ops,
335	},
336	.probe = ks8851_probe_par,
337	.remove_new = ks8851_remove_par,
338};
339module_platform_driver(ks8851_driver);
340
341MODULE_DESCRIPTION("KS8851 Network driver");
342MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
343MODULE_LICENSE("GPL");
344
345module_param_named(message, msg_enable, int, 0);
346MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
347