1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Software PHY emulation
4  *
5  * Code taken from fixed_phy.c by Russell King.
6  *
7  * Author: Vitaly Bordug <vbordug@ru.mvista.com>
8  *         Anton Vorontsov <avorontsov@ru.mvista.com>
9  *
10  * Copyright (c) 2006-2007 MontaVista Software, Inc.
11  */
12 #include <linux/export.h>
13 #include <linux/mii.h>
14 #include <linux/phy.h>
15 #include <linux/phy_fixed.h>
16 
17 #include "swphy.h"
18 
19 #define MII_REGS_NUM 29
20 
21 struct swmii_regs {
22 	u16 bmsr;
23 	u16 lpa;
24 	u16 lpagb;
25 	u16 estat;
26 };
27 
28 enum {
29 	SWMII_SPEED_10 = 0,
30 	SWMII_SPEED_100,
31 	SWMII_SPEED_1000,
32 	SWMII_DUPLEX_HALF = 0,
33 	SWMII_DUPLEX_FULL,
34 };
35 
36 /*
37  * These two tables get bitwise-anded together to produce the final result.
38  * This means the speed table must contain both duplex settings, and the
39  * duplex table must contain all speed settings.
40  */
41 static const struct swmii_regs speed[] = {
42 	[SWMII_SPEED_10] = {
43 		.lpa   = LPA_10FULL | LPA_10HALF,
44 	},
45 	[SWMII_SPEED_100] = {
46 		.bmsr  = BMSR_100FULL | BMSR_100HALF,
47 		.lpa   = LPA_100FULL | LPA_100HALF,
48 	},
49 	[SWMII_SPEED_1000] = {
50 		.bmsr  = BMSR_ESTATEN,
51 		.lpagb = LPA_1000FULL | LPA_1000HALF,
52 		.estat = ESTATUS_1000_TFULL | ESTATUS_1000_THALF,
53 	},
54 };
55 
56 static const struct swmii_regs duplex[] = {
57 	[SWMII_DUPLEX_HALF] = {
58 		.bmsr  = BMSR_ESTATEN | BMSR_100HALF,
59 		.lpa   = LPA_10HALF | LPA_100HALF,
60 		.lpagb = LPA_1000HALF,
61 		.estat = ESTATUS_1000_THALF,
62 	},
63 	[SWMII_DUPLEX_FULL] = {
64 		.bmsr  = BMSR_ESTATEN | BMSR_100FULL,
65 		.lpa   = LPA_10FULL | LPA_100FULL,
66 		.lpagb = LPA_1000FULL,
67 		.estat = ESTATUS_1000_TFULL,
68 	},
69 };
70 
swphy_decode_speed(int speed)71 static int swphy_decode_speed(int speed)
72 {
73 	switch (speed) {
74 	case 1000:
75 		return SWMII_SPEED_1000;
76 	case 100:
77 		return SWMII_SPEED_100;
78 	case 10:
79 		return SWMII_SPEED_10;
80 	default:
81 		return -EINVAL;
82 	}
83 }
84 
85 /**
86  * swphy_validate_state - validate the software phy status
87  * @state: software phy status
88  *
89  * This checks that we can represent the state stored in @state can be
90  * represented in the emulated MII registers.  Returns 0 if it can,
91  * otherwise returns -EINVAL.
92  */
swphy_validate_state(const struct fixed_phy_status * state)93 int swphy_validate_state(const struct fixed_phy_status *state)
94 {
95 	int err;
96 
97 	if (state->link) {
98 		err = swphy_decode_speed(state->speed);
99 		if (err < 0) {
100 			pr_warn("swphy: unknown speed\n");
101 			return -EINVAL;
102 		}
103 	}
104 	return 0;
105 }
106 EXPORT_SYMBOL_GPL(swphy_validate_state);
107 
108 /**
109  * swphy_read_reg - return a MII register from the fixed phy state
110  * @reg: MII register
111  * @state: fixed phy status
112  *
113  * Return the MII @reg register generated from the fixed phy state @state.
114  */
swphy_read_reg(int reg,const struct fixed_phy_status * state)115 int swphy_read_reg(int reg, const struct fixed_phy_status *state)
116 {
117 	int speed_index, duplex_index;
118 	u16 bmsr = BMSR_ANEGCAPABLE;
119 	u16 estat = 0;
120 	u16 lpagb = 0;
121 	u16 lpa = 0;
122 
123 	if (reg > MII_REGS_NUM)
124 		return -1;
125 
126 	speed_index = swphy_decode_speed(state->speed);
127 	if (WARN_ON(speed_index < 0))
128 		return 0;
129 
130 	duplex_index = state->duplex ? SWMII_DUPLEX_FULL : SWMII_DUPLEX_HALF;
131 
132 	bmsr |= speed[speed_index].bmsr & duplex[duplex_index].bmsr;
133 	estat |= speed[speed_index].estat & duplex[duplex_index].estat;
134 
135 	if (state->link) {
136 		bmsr |= BMSR_LSTATUS | BMSR_ANEGCOMPLETE;
137 
138 		lpa   |= speed[speed_index].lpa   & duplex[duplex_index].lpa;
139 		lpagb |= speed[speed_index].lpagb & duplex[duplex_index].lpagb;
140 
141 		if (state->pause)
142 			lpa |= LPA_PAUSE_CAP;
143 
144 		if (state->asym_pause)
145 			lpa |= LPA_PAUSE_ASYM;
146 	}
147 
148 	switch (reg) {
149 	case MII_BMCR:
150 		return BMCR_ANENABLE;
151 	case MII_BMSR:
152 		return bmsr;
153 	case MII_PHYSID1:
154 	case MII_PHYSID2:
155 		return 0;
156 	case MII_LPA:
157 		return lpa;
158 	case MII_STAT1000:
159 		return lpagb;
160 	case MII_ESTATUS:
161 		return estat;
162 
163 	/*
164 	 * We do not support emulating Clause 45 over Clause 22 register
165 	 * reads.  Return an error instead of bogus data.
166 	 */
167 	case MII_MMD_CTRL:
168 	case MII_MMD_DATA:
169 		return -1;
170 
171 	default:
172 		return 0xffff;
173 	}
174 }
175 EXPORT_SYMBOL_GPL(swphy_read_reg);
176