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1 From d19ad7515a7ef4ee58b5c6606ee9f74c94f28932 Mon Sep 17 00:00:00 2001
2 From: Weijie Gao <weijie.gao@mediatek.com>
3 Date: Wed, 31 Aug 2022 19:04:32 +0800
4 Subject: [PATCH 10/32] serial: mtk: add support for using dynamic baud clock
5 souce
6
7 The baud clock on some platform may change due to assigned-clock-parent
8 set in DT. In current flow the baud clock is only retrieved during probe
9 stage. If the parent of the source clock changes after probe stage, the
10 setbrg will set wrong baudrate.
11
12 To get the right clock rate, this patch records the baud clk struct to the
13 driver's priv, and changes the driver's flow to get the clock rate before
14 calling _mtk_serial_setbrg().
15
16 Reviewed-by: Simon Glass <sjg@chromium.org>
17 Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
18 ---
19 drivers/serial/serial_mtk.c | 80 ++++++++++++++++++++++---------------
20 1 file changed, 47 insertions(+), 33 deletions(-)
21
22 --- a/drivers/serial/serial_mtk.c
23 +++ b/drivers/serial/serial_mtk.c
24 @@ -10,6 +10,7 @@
25 #include <common.h>
26 #include <div64.h>
27 #include <dm.h>
28 +#include <dm/device_compat.h>
29 #include <errno.h>
30 #include <log.h>
31 #include <serial.h>
32 @@ -70,27 +71,37 @@ struct mtk_serial_regs {
33 #define BAUD_ALLOW_MAX(baud) ((baud) + (baud) * 3 / 100)
34 #define BAUD_ALLOW_MIX(baud) ((baud) - (baud) * 3 / 100)
35
36 +/* struct mtk_serial_priv - Structure holding all information used by the
37 + * driver
38 + * @regs: Register base of the serial port
39 + * @clk: The baud clock device
40 + * @fixed_clk_rate: Fallback fixed baud clock rate if baud clock
41 + * device is not specified
42 + * @force_highspeed: Force using high-speed mode
43 + */
44 struct mtk_serial_priv {
45 struct mtk_serial_regs __iomem *regs;
46 - u32 clock;
47 + struct clk clk;
48 + u32 fixed_clk_rate;
49 bool force_highspeed;
50 };
51
52 -static void _mtk_serial_setbrg(struct mtk_serial_priv *priv, int baud)
53 +static void _mtk_serial_setbrg(struct mtk_serial_priv *priv, int baud,
54 + uint clk_rate)
55 {
56 u32 quot, realbaud, samplecount = 1;
57
58 /* Special case for low baud clock */
59 - if (baud <= 115200 && priv->clock <= 12000000) {
60 + if (baud <= 115200 && clk_rate == 12000000) {
61 writel(3, &priv->regs->highspeed);
62
63 - quot = DIV_ROUND_CLOSEST(priv->clock, 256 * baud);
64 + quot = DIV_ROUND_CLOSEST(clk_rate, 256 * baud);
65 if (quot == 0)
66 quot = 1;
67
68 - samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
69 + samplecount = DIV_ROUND_CLOSEST(clk_rate, quot * baud);
70
71 - realbaud = priv->clock / samplecount / quot;
72 + realbaud = clk_rate / samplecount / quot;
73 if (realbaud > BAUD_ALLOW_MAX(baud) ||
74 realbaud < BAUD_ALLOW_MIX(baud)) {
75 pr_info("baud %d can't be handled\n", baud);
76 @@ -104,7 +115,7 @@ static void _mtk_serial_setbrg(struct mt
77
78 if (baud <= 115200) {
79 writel(0, &priv->regs->highspeed);
80 - quot = DIV_ROUND_CLOSEST(priv->clock, 16 * baud);
81 + quot = DIV_ROUND_CLOSEST(clk_rate, 16 * baud);
82 } else if (baud <= 576000) {
83 writel(2, &priv->regs->highspeed);
84
85 @@ -112,13 +123,13 @@ static void _mtk_serial_setbrg(struct mt
86 if ((baud == 500000) || (baud == 576000))
87 baud = 460800;
88
89 - quot = DIV_ROUND_UP(priv->clock, 4 * baud);
90 + quot = DIV_ROUND_UP(clk_rate, 4 * baud);
91 } else {
92 use_hs3:
93 writel(3, &priv->regs->highspeed);
94
95 - quot = DIV_ROUND_UP(priv->clock, 256 * baud);
96 - samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
97 + quot = DIV_ROUND_UP(clk_rate, 256 * baud);
98 + samplecount = DIV_ROUND_CLOSEST(clk_rate, quot * baud);
99 }
100
101 set_baud:
102 @@ -167,8 +178,13 @@ static int _mtk_serial_pending(struct mt
103 static int mtk_serial_setbrg(struct udevice *dev, int baudrate)
104 {
105 struct mtk_serial_priv *priv = dev_get_priv(dev);
106 + u32 clk_rate;
107 +
108 + clk_rate = clk_get_rate(&priv->clk);
109 + if (IS_ERR_VALUE(clk_rate) || clk_rate == 0)
110 + clk_rate = priv->fixed_clk_rate;
111
112 - _mtk_serial_setbrg(priv, baudrate);
113 + _mtk_serial_setbrg(priv, baudrate, clk_rate);
114
115 return 0;
116 }
117 @@ -211,7 +227,6 @@ static int mtk_serial_of_to_plat(struct
118 {
119 struct mtk_serial_priv *priv = dev_get_priv(dev);
120 fdt_addr_t addr;
121 - struct clk clk;
122 int err;
123
124 addr = dev_read_addr(dev);
125 @@ -220,22 +235,19 @@ static int mtk_serial_of_to_plat(struct
126
127 priv->regs = map_physmem(addr, 0, MAP_NOCACHE);
128
129 - err = clk_get_by_index(dev, 0, &clk);
130 - if (!err) {
131 - err = clk_get_rate(&clk);
132 - if (!IS_ERR_VALUE(err))
133 - priv->clock = err;
134 - } else if (err != -ENOENT && err != -ENODEV && err != -ENOSYS) {
135 - debug("mtk_serial: failed to get clock\n");
136 - return err;
137 - }
138 -
139 - if (!priv->clock)
140 - priv->clock = dev_read_u32_default(dev, "clock-frequency", 0);
141 -
142 - if (!priv->clock) {
143 - debug("mtk_serial: clock not defined\n");
144 - return -EINVAL;
145 + err = clk_get_by_index(dev, 0, &priv->clk);
146 + if (err) {
147 + err = dev_read_u32(dev, "clock-frequency", &priv->fixed_clk_rate);
148 + if (err) {
149 + dev_err(dev, "baud clock not defined\n");
150 + return -EINVAL;
151 + }
152 + } else {
153 + err = clk_get_rate(&priv->clk);
154 + if (IS_ERR_VALUE(err)) {
155 + dev_err(dev, "invalid baud clock\n");
156 + return -EINVAL;
157 + }
158 }
159
160 priv->force_highspeed = dev_read_bool(dev, "mediatek,force-highspeed");
161 @@ -273,7 +285,7 @@ DECLARE_GLOBAL_DATA_PTR;
162 #define DECLARE_HSUART_PRIV(port) \
163 static struct mtk_serial_priv mtk_hsuart##port = { \
164 .regs = (struct mtk_serial_regs *)CONFIG_SYS_NS16550_COM##port, \
165 - .clock = CONFIG_SYS_NS16550_CLK \
166 + .fixed_clk_rate = CONFIG_SYS_NS16550_CLK \
167 };
168
169 #define DECLARE_HSUART_FUNCTIONS(port) \
170 @@ -282,12 +294,14 @@ DECLARE_GLOBAL_DATA_PTR;
171 writel(0, &mtk_hsuart##port.regs->ier); \
172 writel(UART_MCRVAL, &mtk_hsuart##port.regs->mcr); \
173 writel(UART_FCRVAL, &mtk_hsuart##port.regs->fcr); \
174 - _mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate); \
175 + _mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate, \
176 + mtk_hsuart##port.fixed_clk_rate); \
177 return 0 ; \
178 } \
179 static void mtk_serial##port##_setbrg(void) \
180 { \
181 - _mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate); \
182 + _mtk_serial_setbrg(&mtk_hsuart##port, gd->baudrate, \
183 + mtk_hsuart##port.fixed_clk_rate); \
184 } \
185 static int mtk_serial##port##_getc(void) \
186 { \
187 @@ -427,13 +441,13 @@ static inline void _debug_uart_init(void
188 struct mtk_serial_priv priv;
189
190 priv.regs = (void *) CONFIG_VAL(DEBUG_UART_BASE);
191 - priv.clock = CONFIG_DEBUG_UART_CLOCK;
192 + priv.fixed_clk_rate = CONFIG_DEBUG_UART_CLOCK;
193
194 writel(0, &priv.regs->ier);
195 writel(UART_MCRVAL, &priv.regs->mcr);
196 writel(UART_FCRVAL, &priv.regs->fcr);
197
198 - _mtk_serial_setbrg(&priv, CONFIG_BAUDRATE);
199 + _mtk_serial_setbrg(&priv, CONFIG_BAUDRATE, priv.fixed_clk_rate);
200 }
201
202 static inline void _debug_uart_putc(int ch)
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