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Linux/drivers/cpufreq/kirkwood-cpufreq.c

  1 /*
  2  *      kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
  3  *
  4  *      Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
  5  *
  6  *      This program is free software; you can redistribute it and/or
  7  *      modify it under the terms of the GNU General Public License
  8  *      as published by the Free Software Foundation; either version
  9  *      2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #include <linux/kernel.h>
 13 #include <linux/module.h>
 14 #include <linux/clk.h>
 15 #include <linux/clk-provider.h>
 16 #include <linux/cpufreq.h>
 17 #include <linux/of_device.h>
 18 #include <linux/platform_device.h>
 19 #include <linux/io.h>
 20 #include <asm/proc-fns.h>
 21 
 22 #define CPU_SW_INT_BLK BIT(28)
 23 
 24 static struct priv
 25 {
 26         struct clk *cpu_clk;
 27         struct clk *ddr_clk;
 28         struct clk *powersave_clk;
 29         struct device *dev;
 30         void __iomem *base;
 31 } priv;
 32 
 33 #define STATE_CPU_FREQ 0x01
 34 #define STATE_DDR_FREQ 0x02
 35 
 36 /*
 37  * Kirkwood can swap the clock to the CPU between two clocks:
 38  *
 39  * - cpu clk
 40  * - ddr clk
 41  *
 42  * The frequencies are set at runtime before registering this *
 43  * table.
 44  */
 45 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
 46         {STATE_CPU_FREQ,        0}, /* CPU uses cpuclk */
 47         {STATE_DDR_FREQ,        0}, /* CPU uses ddrclk */
 48         {0,                     CPUFREQ_TABLE_END},
 49 };
 50 
 51 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
 52 {
 53         if (__clk_is_enabled(priv.powersave_clk))
 54                 return kirkwood_freq_table[1].frequency;
 55         return kirkwood_freq_table[0].frequency;
 56 }
 57 
 58 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
 59                             unsigned int index)
 60 {
 61         unsigned int state = kirkwood_freq_table[index].driver_data;
 62         unsigned long reg;
 63 
 64         local_irq_disable();
 65 
 66         /* Disable interrupts to the CPU */
 67         reg = readl_relaxed(priv.base);
 68         reg |= CPU_SW_INT_BLK;
 69         writel_relaxed(reg, priv.base);
 70 
 71         switch (state) {
 72         case STATE_CPU_FREQ:
 73                 clk_disable(priv.powersave_clk);
 74                 break;
 75         case STATE_DDR_FREQ:
 76                 clk_enable(priv.powersave_clk);
 77                 break;
 78         }
 79 
 80         /* Wait-for-Interrupt, while the hardware changes frequency */
 81         cpu_do_idle();
 82 
 83         /* Enable interrupts to the CPU */
 84         reg = readl_relaxed(priv.base);
 85         reg &= ~CPU_SW_INT_BLK;
 86         writel_relaxed(reg, priv.base);
 87 
 88         local_irq_enable();
 89 
 90         return 0;
 91 }
 92 
 93 /* Module init and exit code */
 94 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
 95 {
 96         return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
 97 }
 98 
 99 static struct cpufreq_driver kirkwood_cpufreq_driver = {
100         .flags  = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
101         .get    = kirkwood_cpufreq_get_cpu_frequency,
102         .verify = cpufreq_generic_frequency_table_verify,
103         .target_index = kirkwood_cpufreq_target,
104         .init   = kirkwood_cpufreq_cpu_init,
105         .exit   = cpufreq_generic_exit,
106         .name   = "kirkwood-cpufreq",
107         .attr   = cpufreq_generic_attr,
108 };
109 
110 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
111 {
112         struct device_node *np;
113         struct resource *res;
114         int err;
115 
116         priv.dev = &pdev->dev;
117 
118         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
119         priv.base = devm_ioremap_resource(&pdev->dev, res);
120         if (IS_ERR(priv.base))
121                 return PTR_ERR(priv.base);
122 
123         np = of_cpu_device_node_get(0);
124         if (!np) {
125                 dev_err(&pdev->dev, "failed to get cpu device node\n");
126                 return -ENODEV;
127         }
128 
129         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
130         if (IS_ERR(priv.cpu_clk)) {
131                 dev_err(priv.dev, "Unable to get cpuclk");
132                 return PTR_ERR(priv.cpu_clk);
133         }
134 
135         clk_prepare_enable(priv.cpu_clk);
136         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
137 
138         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
139         if (IS_ERR(priv.ddr_clk)) {
140                 dev_err(priv.dev, "Unable to get ddrclk");
141                 err = PTR_ERR(priv.ddr_clk);
142                 goto out_cpu;
143         }
144 
145         clk_prepare_enable(priv.ddr_clk);
146         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
147 
148         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
149         if (IS_ERR(priv.powersave_clk)) {
150                 dev_err(priv.dev, "Unable to get powersave");
151                 err = PTR_ERR(priv.powersave_clk);
152                 goto out_ddr;
153         }
154         clk_prepare(priv.powersave_clk);
155 
156         of_node_put(np);
157         np = NULL;
158 
159         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
160         if (!err)
161                 return 0;
162 
163         dev_err(priv.dev, "Failed to register cpufreq driver");
164 
165         clk_disable_unprepare(priv.powersave_clk);
166 out_ddr:
167         clk_disable_unprepare(priv.ddr_clk);
168 out_cpu:
169         clk_disable_unprepare(priv.cpu_clk);
170         of_node_put(np);
171 
172         return err;
173 }
174 
175 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
176 {
177         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
178 
179         clk_disable_unprepare(priv.powersave_clk);
180         clk_disable_unprepare(priv.ddr_clk);
181         clk_disable_unprepare(priv.cpu_clk);
182 
183         return 0;
184 }
185 
186 static struct platform_driver kirkwood_cpufreq_platform_driver = {
187         .probe = kirkwood_cpufreq_probe,
188         .remove = kirkwood_cpufreq_remove,
189         .driver = {
190                 .name = "kirkwood-cpufreq",
191                 .owner = THIS_MODULE,
192         },
193 };
194 
195 module_platform_driver(kirkwood_cpufreq_platform_driver);
196 
197 MODULE_LICENSE("GPL v2");
198 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
199 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
200 MODULE_ALIAS("platform:kirkwood-cpufreq");
201 

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