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 
25 static 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  */
45 struct 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  */
62 static 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  */
76 static 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  */
91 static 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  */
135 static 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  */
152 static 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  */
170 static 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  */
191 static 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 
213 /**
214  * ks8851_rx_skb_par - receive skbuff
215  * @ks: The device state.
216  * @skb: The skbuff
217  */
218 static void ks8851_rx_skb_par(struct ks8851_net *ks, struct sk_buff *skb)
219 {
220 	netif_rx(skb);
221 }
222 
223 static unsigned int ks8851_rdreg16_par_txqcr(struct ks8851_net *ks)
224 {
225 	return ks8851_rdreg16_par(ks, KS_TXQCR);
226 }
227 
228 /**
229  * ks8851_start_xmit_par - transmit packet
230  * @skb: The buffer to transmit
231  * @dev: The device used to transmit the packet.
232  *
233  * Called by the network layer to transmit the @skb. Queue the packet for
234  * the device and schedule the necessary work to transmit the packet when
235  * it is free.
236  *
237  * We do this to firstly avoid sleeping with the network device locked,
238  * and secondly so we can round up more than one packet to transmit which
239  * means we can try and avoid generating too many transmit done interrupts.
240  */
241 static netdev_tx_t ks8851_start_xmit_par(struct sk_buff *skb,
242 					 struct net_device *dev)
243 {
244 	struct ks8851_net *ks = netdev_priv(dev);
245 	netdev_tx_t ret = NETDEV_TX_OK;
246 	unsigned long flags;
247 	unsigned int txqcr;
248 	u16 txmir;
249 	int err;
250 
251 	netif_dbg(ks, tx_queued, ks->netdev,
252 		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);
253 
254 	ks8851_lock_par(ks, &flags);
255 
256 	txmir = ks8851_rdreg16_par(ks, KS_TXMIR) & 0x1fff;
257 
258 	if (likely(txmir >= skb->len + 12)) {
259 		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);
260 		ks8851_wrfifo_par(ks, skb, false);
261 		ks8851_wrreg16_par(ks, KS_RXQCR, ks->rc_rxqcr);
262 		ks8851_wrreg16_par(ks, KS_TXQCR, TXQCR_METFE);
263 
264 		err = readx_poll_timeout_atomic(ks8851_rdreg16_par_txqcr, ks,
265 						txqcr, !(txqcr & TXQCR_METFE),
266 						5, 1000000);
267 		if (err)
268 			ret = NETDEV_TX_BUSY;
269 
270 		ks8851_done_tx(ks, skb);
271 	} else {
272 		ret = NETDEV_TX_BUSY;
273 	}
274 
275 	ks8851_unlock_par(ks, &flags);
276 
277 	return ret;
278 }
279 
280 static int ks8851_probe_par(struct platform_device *pdev)
281 {
282 	struct device *dev = &pdev->dev;
283 	struct ks8851_net_par *ksp;
284 	struct net_device *netdev;
285 	struct ks8851_net *ks;
286 	int ret;
287 
288 	netdev = devm_alloc_etherdev(dev, sizeof(struct ks8851_net_par));
289 	if (!netdev)
290 		return -ENOMEM;
291 
292 	ks = netdev_priv(netdev);
293 
294 	ks->lock = ks8851_lock_par;
295 	ks->unlock = ks8851_unlock_par;
296 	ks->rdreg16 = ks8851_rdreg16_par;
297 	ks->wrreg16 = ks8851_wrreg16_par;
298 	ks->rdfifo = ks8851_rdfifo_par;
299 	ks->wrfifo = ks8851_wrfifo_par;
300 	ks->start_xmit = ks8851_start_xmit_par;
301 	ks->rx_skb = ks8851_rx_skb_par;
302 
303 #define STD_IRQ (IRQ_LCI |	/* Link Change */	\
304 		 IRQ_RXI |	/* RX done */		\
305 		 IRQ_RXPSI)	/* RX process stop */
306 	ks->rc_ier = STD_IRQ;
307 
308 	ksp = to_ks8851_par(ks);
309 	spin_lock_init(&ksp->lock);
310 
311 	ksp->hw_addr = devm_platform_ioremap_resource(pdev, 0);
312 	if (IS_ERR(ksp->hw_addr))
313 		return PTR_ERR(ksp->hw_addr);
314 
315 	ksp->hw_addr_cmd = devm_platform_ioremap_resource(pdev, 1);
316 	if (IS_ERR(ksp->hw_addr_cmd))
317 		return PTR_ERR(ksp->hw_addr_cmd);
318 
319 	ret = ks_check_endian(ks);
320 	if (ret)
321 		return ret;
322 
323 	netdev->irq = platform_get_irq(pdev, 0);
324 
325 	return ks8851_probe_common(netdev, dev, msg_enable);
326 }
327 
328 static int ks8851_remove_par(struct platform_device *pdev)
329 {
330 	return ks8851_remove_common(&pdev->dev);
331 }
332 
333 static const struct of_device_id ks8851_match_table[] = {
334 	{ .compatible = "micrel,ks8851-mll" },
335 	{ }
336 };
337 MODULE_DEVICE_TABLE(of, ks8851_match_table);
338 
339 static struct platform_driver ks8851_driver = {
340 	.driver = {
341 		.name = "ks8851",
342 		.of_match_table = ks8851_match_table,
343 		.pm = &ks8851_pm_ops,
344 	},
345 	.probe = ks8851_probe_par,
346 	.remove = ks8851_remove_par,
347 };
348 module_platform_driver(ks8851_driver);
349 
350 MODULE_DESCRIPTION("KS8851 Network driver");
351 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
352 MODULE_LICENSE("GPL");
353 
354 module_param_named(message, msg_enable, int, 0);
355 MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
356