| /* |
| * Copyright (C) Maxime Coquelin 2015 |
| * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com> |
| * License terms: GNU General Public License (GPL), version 2 |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/clocksource.h> |
| #include <linux/clockchips.h> |
| #include <linux/io.h> |
| #include <linux/of.h> |
| #include <linux/of_address.h> |
| #include <linux/clk.h> |
| #include <linux/bitops.h> |
| |
| #define SYST_CSR 0x00 |
| #define SYST_RVR 0x04 |
| #define SYST_CVR 0x08 |
| #define SYST_CALIB 0x0c |
| |
| #define SYST_CSR_ENABLE BIT(0) |
| |
| #define SYSTICK_LOAD_RELOAD_MASK 0x00FFFFFF |
| |
| static int __init system_timer_of_register(struct device_node *np) |
| { |
| struct clk *clk = NULL; |
| void __iomem *base; |
| u32 rate; |
| int ret; |
| |
| base = of_iomap(np, 0); |
| if (!base) { |
| pr_warn("system-timer: invalid base address\n"); |
| return -ENXIO; |
| } |
| |
| ret = of_property_read_u32(np, "clock-frequency", &rate); |
| if (ret) { |
| clk = of_clk_get(np, 0); |
| if (IS_ERR(clk)) { |
| ret = PTR_ERR(clk); |
| goto out_unmap; |
| } |
| |
| ret = clk_prepare_enable(clk); |
| if (ret) |
| goto out_clk_put; |
| |
| rate = clk_get_rate(clk); |
| if (!rate) { |
| ret = -EINVAL; |
| goto out_clk_disable; |
| } |
| } |
| |
| writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); |
| writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); |
| |
| ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", rate, |
| 200, 24, clocksource_mmio_readl_down); |
| if (ret) { |
| pr_err("failed to init clocksource (%d)\n", ret); |
| if (clk) |
| goto out_clk_disable; |
| else |
| goto out_unmap; |
| } |
| |
| pr_info("ARM System timer initialized as clocksource\n"); |
| |
| return 0; |
| |
| out_clk_disable: |
| clk_disable_unprepare(clk); |
| out_clk_put: |
| clk_put(clk); |
| out_unmap: |
| iounmap(base); |
| pr_warn("ARM System timer register failed (%d)\n", ret); |
| |
| return ret; |
| } |
| |
| TIMER_OF_DECLARE(arm_systick, "arm,armv7m-systick", |
| system_timer_of_register); |