1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // mcp251xfd - Microchip MCP251xFD Family CAN controller driver
4 //
5 // Copyright (c) 2021, 2022 Pengutronix,
6 // Marc Kleine-Budde <kernel@pengutronix.de>
7 //
8
9 #include "mcp251xfd-ram.h"
10
can_ram_clamp(const struct can_ram_config * config,const struct can_ram_obj_config * obj,u8 val)11 static inline u8 can_ram_clamp(const struct can_ram_config *config,
12 const struct can_ram_obj_config *obj,
13 u8 val)
14 {
15 u8 max;
16
17 max = min_t(u8, obj->max, obj->fifo_num * config->fifo_depth);
18 return clamp(val, obj->min, max);
19 }
20
21 static u8
can_ram_rounddown_pow_of_two(const struct can_ram_config * config,const struct can_ram_obj_config * obj,const u8 coalesce,u8 val)22 can_ram_rounddown_pow_of_two(const struct can_ram_config *config,
23 const struct can_ram_obj_config *obj,
24 const u8 coalesce, u8 val)
25 {
26 u8 fifo_num = obj->fifo_num;
27 u8 ret = 0, i;
28
29 val = can_ram_clamp(config, obj, val);
30
31 if (coalesce) {
32 /* Use 1st FIFO for coalescing, if requested.
33 *
34 * Either use complete FIFO (and FIFO Full IRQ) for
35 * coalescing or only half of FIFO (FIFO Half Full
36 * IRQ) and use remaining half for normal objects.
37 */
38 ret = min_t(u8, coalesce * 2, config->fifo_depth);
39 val -= ret;
40 fifo_num--;
41 }
42
43 for (i = 0; i < fifo_num && val; i++) {
44 u8 n;
45
46 n = min_t(u8, rounddown_pow_of_two(val),
47 config->fifo_depth);
48
49 /* skip small FIFOs */
50 if (n < obj->fifo_depth_min)
51 return ret;
52
53 ret += n;
54 val -= n;
55 }
56
57 return ret;
58 }
59
can_ram_get_layout(struct can_ram_layout * layout,const struct can_ram_config * config,const struct ethtool_ringparam * ring,const struct ethtool_coalesce * ec,const bool fd_mode)60 void can_ram_get_layout(struct can_ram_layout *layout,
61 const struct can_ram_config *config,
62 const struct ethtool_ringparam *ring,
63 const struct ethtool_coalesce *ec,
64 const bool fd_mode)
65 {
66 u8 num_rx, num_tx;
67 u16 ram_free;
68
69 /* default CAN */
70
71 num_tx = config->tx.def[fd_mode];
72 num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, 0, num_tx);
73
74 ram_free = config->size;
75 ram_free -= config->tx.size[fd_mode] * num_tx;
76
77 num_rx = ram_free / config->rx.size[fd_mode];
78
79 layout->default_rx = can_ram_rounddown_pow_of_two(config, &config->rx, 0, num_rx);
80 layout->default_tx = num_tx;
81
82 /* MAX CAN */
83
84 ram_free = config->size;
85 ram_free -= config->tx.size[fd_mode] * config->tx.min;
86 num_rx = ram_free / config->rx.size[fd_mode];
87
88 ram_free = config->size;
89 ram_free -= config->rx.size[fd_mode] * config->rx.min;
90 num_tx = ram_free / config->tx.size[fd_mode];
91
92 layout->max_rx = can_ram_rounddown_pow_of_two(config, &config->rx, 0, num_rx);
93 layout->max_tx = can_ram_rounddown_pow_of_two(config, &config->tx, 0, num_tx);
94
95 /* cur CAN */
96
97 if (ring) {
98 u8 num_rx_coalesce = 0, num_tx_coalesce = 0;
99
100 /* If the ring parameters have been configured in
101 * CAN-CC mode, but and we are in CAN-FD mode now,
102 * they might be to big. Use the default CAN-FD values
103 * in this case.
104 */
105 num_rx = ring->rx_pending;
106 if (num_rx > layout->max_rx)
107 num_rx = layout->default_rx;
108
109 num_rx = can_ram_rounddown_pow_of_two(config, &config->rx, 0, num_rx);
110
111 /* The ethtool doc says:
112 * To disable coalescing, set usecs = 0 and max_frames = 1.
113 */
114 if (ec && !(ec->rx_coalesce_usecs_irq == 0 &&
115 ec->rx_max_coalesced_frames_irq == 1)) {
116 u8 max;
117
118 /* use only max half of available objects for coalescing */
119 max = min_t(u8, num_rx / 2, config->fifo_depth);
120 num_rx_coalesce = clamp(ec->rx_max_coalesced_frames_irq,
121 (u32)config->rx.fifo_depth_coalesce_min,
122 (u32)max);
123 num_rx_coalesce = rounddown_pow_of_two(num_rx_coalesce);
124
125 num_rx = can_ram_rounddown_pow_of_two(config, &config->rx,
126 num_rx_coalesce, num_rx);
127 }
128
129 ram_free = config->size - config->rx.size[fd_mode] * num_rx;
130 num_tx = ram_free / config->tx.size[fd_mode];
131 num_tx = min_t(u8, ring->tx_pending, num_tx);
132 num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, 0, num_tx);
133
134 /* The ethtool doc says:
135 * To disable coalescing, set usecs = 0 and max_frames = 1.
136 */
137 if (ec && !(ec->tx_coalesce_usecs_irq == 0 &&
138 ec->tx_max_coalesced_frames_irq == 1)) {
139 u8 max;
140
141 /* use only max half of available objects for coalescing */
142 max = min_t(u8, num_tx / 2, config->fifo_depth);
143 num_tx_coalesce = clamp(ec->tx_max_coalesced_frames_irq,
144 (u32)config->tx.fifo_depth_coalesce_min,
145 (u32)max);
146 num_tx_coalesce = rounddown_pow_of_two(num_tx_coalesce);
147
148 num_tx = can_ram_rounddown_pow_of_two(config, &config->tx,
149 num_tx_coalesce, num_tx);
150 }
151
152 layout->cur_rx = num_rx;
153 layout->cur_tx = num_tx;
154 layout->rx_coalesce = num_rx_coalesce;
155 layout->tx_coalesce = num_tx_coalesce;
156 } else {
157 layout->cur_rx = layout->default_rx;
158 layout->cur_tx = layout->default_tx;
159 layout->rx_coalesce = 0;
160 layout->tx_coalesce = 0;
161 }
162 }
163