1 /*
2 * Copyright (C) 2014 Free Electrons
3 *
4 * License Terms: GNU General Public License v2
5 * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
6 *
7 * Allwinner A31 AR100 clock driver
8 *
9 */
10
11 #include <linux/bitops.h>
12 #include <linux/clk-provider.h>
13 #include <linux/init.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/spinlock.h>
17
18 #include "clk-factors.h"
19
20 /**
21 * sun6i_get_ar100_factors - Calculates factors p, m for AR100
22 *
23 * AR100 rate is calculated as follows
24 * rate = (parent_rate >> p) / (m + 1);
25 */
sun6i_get_ar100_factors(struct factors_request * req)26 static void sun6i_get_ar100_factors(struct factors_request *req)
27 {
28 unsigned long div;
29 int shift;
30
31 /* clock only divides */
32 if (req->rate > req->parent_rate)
33 req->rate = req->parent_rate;
34
35 div = DIV_ROUND_UP(req->parent_rate, req->rate);
36
37 if (div < 32)
38 shift = 0;
39 else if (div >> 1 < 32)
40 shift = 1;
41 else if (div >> 2 < 32)
42 shift = 2;
43 else
44 shift = 3;
45
46 div >>= shift;
47
48 if (div > 32)
49 div = 32;
50
51 req->rate = (req->parent_rate >> shift) / div;
52 req->m = div - 1;
53 req->p = shift;
54 }
55
56 static const struct clk_factors_config sun6i_ar100_config = {
57 .mwidth = 5,
58 .mshift = 8,
59 .pwidth = 2,
60 .pshift = 4,
61 };
62
63 static const struct factors_data sun6i_ar100_data = {
64 .mux = 16,
65 .muxmask = GENMASK(1, 0),
66 .table = &sun6i_ar100_config,
67 .getter = sun6i_get_ar100_factors,
68 };
69
70 static DEFINE_SPINLOCK(sun6i_ar100_lock);
71
sun6i_a31_ar100_clk_probe(struct platform_device * pdev)72 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
73 {
74 struct device_node *np = pdev->dev.of_node;
75 struct resource *r;
76 void __iomem *reg;
77 struct clk *clk;
78
79 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
80 reg = devm_ioremap_resource(&pdev->dev, r);
81 if (IS_ERR(reg))
82 return PTR_ERR(reg);
83
84 clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
85 reg);
86 if (!clk)
87 return -ENOMEM;
88
89 platform_set_drvdata(pdev, clk);
90
91 return 0;
92 }
93
94 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
95 { .compatible = "allwinner,sun6i-a31-ar100-clk" },
96 { /* sentinel */ }
97 };
98
99 static struct platform_driver sun6i_a31_ar100_clk_driver = {
100 .driver = {
101 .name = "sun6i-a31-ar100-clk",
102 .of_match_table = sun6i_a31_ar100_clk_dt_ids,
103 .suppress_bind_attrs = true,
104 },
105 .probe = sun6i_a31_ar100_clk_probe,
106 };
107 builtin_platform_driver(sun6i_a31_ar100_clk_driver);
108
