--- /dev/null
+/*
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Thomas Abraham <thomas.ab@samsung.com>
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This file contains the utility function to register CPU clock for Samsung
+ * Exynos platforms. A CPU clock is defined as a clock supplied to a CPU or a
+ * group of CPUs. The CPU clock is typically derived from a hierarchy of clock
+ * blocks which includes mux and divider blocks. There are a number of other
+ * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI
+ * clock for CPU domain. The rates of these auxiliary clocks are related to the
+ * CPU clock rate and this relation is usually specified in the hardware manual
+ * of the SoC or supplied after the SoC characterization.
+ *
+ * The below implementation of the CPU clock allows the rate changes of the CPU
+ * clock and the corresponding rate changes of the auxillary clocks of the CPU
+ * domain. The platform clock driver provides a clock register configuration
+ * for each configurable rate which is then used to program the clock hardware
+ * registers to acheive a fast co-oridinated rate change for all the CPU domain
+ * clocks.
+ *
+ * On a rate change request for the CPU clock, the rate change is propagated
+ * upto the PLL supplying the clock to the CPU domain clock blocks. While the
+ * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an
+ * alternate clock source. If required, the alternate clock source is divided
+ * down in order to keep the output clock rate within the previous OPP limits.
+*/
+
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include "clk-cpu.h"
+
+#define E4210_SRC_CPU 0x0
+#define E4210_STAT_CPU 0x200
+#define E4210_DIV_CPU0 0x300
+#define E4210_DIV_CPU1 0x304
+#define E4210_DIV_STAT_CPU0 0x400
+#define E4210_DIV_STAT_CPU1 0x404
+
+#define E4210_DIV0_RATIO0_MASK 0x7
+#define E4210_DIV1_HPM_MASK (0x7 << 4)
+#define E4210_DIV1_COPY_MASK (0x7 << 0)
+#define E4210_MUX_HPM_MASK (1 << 20)
+#define E4210_DIV0_ATB_SHIFT 16
+#define E4210_DIV0_ATB_MASK (DIV_MASK << E4210_DIV0_ATB_SHIFT)
+
+#define MAX_DIV 8
+#define DIV_MASK 7
+#define DIV_MASK_ALL 0xffffffff
+#define MUX_MASK 7
+
+/*
+ * Helper function to wait until divider(s) have stabilized after the divider
+ * value has changed.
+ */
+static void wait_until_divider_stable(void __iomem *div_reg, unsigned long mask)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(10);
+
+ do {
+ if (!(readl(div_reg) & mask))
+ return;
+ } while (time_before(jiffies, timeout));
+
+ if (!(readl(div_reg) & mask))
+ return;
+
+ pr_err("%s: timeout in divider stablization\n", __func__);
+}
+
+/*
+ * Helper function to wait until mux has stabilized after the mux selection
+ * value was changed.
+ */
+static void wait_until_mux_stable(void __iomem *mux_reg, u32 mux_pos,
+ unsigned long mux_value)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(10);
+
+ do {
+ if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value)
+ return;
+ } while (time_before(jiffies, timeout));
+
+ if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value)
+ return;
+
+ pr_err("%s: re-parenting mux timed-out\n", __func__);
+}
+
+/* common round rate callback useable for all types of CPU clocks */
+static long exynos_cpuclk_round_rate(struct clk_hw *hw,
+ unsigned long drate, unsigned long *prate)
+{
+ struct clk_hw *parent = clk_hw_get_parent(hw);
+ *prate = clk_hw_round_rate(parent, drate);
+ return *prate;
+}
+
+/* common recalc rate callback useable for all types of CPU clocks */
+static unsigned long exynos_cpuclk_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ /*
+ * The CPU clock output (armclk) rate is the same as its parent
+ * rate. Although there exist certain dividers inside the CPU
+ * clock block that could be used to divide the parent clock,
+ * the driver does not make use of them currently, except during
+ * frequency transitions.
+ */
+ return parent_rate;
+}
+
+static const struct clk_ops exynos_cpuclk_clk_ops = {
+ .recalc_rate = exynos_cpuclk_recalc_rate,
+ .round_rate = exynos_cpuclk_round_rate,
+};
+
+/*
+ * Helper function to set the 'safe' dividers for the CPU clock. The parameters
+ * div and mask contain the divider value and the register bit mask of the
+ * dividers to be programmed.
+ */
+static void exynos_set_safe_div(void __iomem *base, unsigned long div,
+ unsigned long mask)
+{
+ unsigned long div0;
+
+ div0 = readl(base + E4210_DIV_CPU0);
+ div0 = (div0 & ~mask) | (div & mask);
+ writel(div0, base + E4210_DIV_CPU0);
+ wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, mask);
+}
+
+/* handler for pre-rate change notification from parent clock */
+static int exynos_cpuclk_pre_rate_change(struct clk_notifier_data *ndata,
+ struct exynos_cpuclk *cpuclk, void __iomem *base)
+{
+ const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
+ unsigned long alt_prate = clk_get_rate(cpuclk->alt_parent);
+ unsigned long alt_div = 0, alt_div_mask = DIV_MASK;
+ unsigned long div0, div1 = 0, mux_reg;
+ unsigned long flags;
+
+ /* find out the divider values to use for clock data */
+ while ((cfg_data->prate * 1000) != ndata->new_rate) {
+ if (cfg_data->prate == 0)
+ return -EINVAL;
+ cfg_data++;
+ }
+
+ spin_lock_irqsave(cpuclk->lock, flags);
+
+ /*
+ * For the selected PLL clock frequency, get the pre-defined divider
+ * values. If the clock for sclk_hpm is not sourced from apll, then
+ * the values for DIV_COPY and DIV_HPM dividers need not be set.
+ */
+ div0 = cfg_data->div0;
+ if (cpuclk->flags & CLK_CPU_HAS_DIV1) {
+ div1 = cfg_data->div1;
+ if (readl(base + E4210_SRC_CPU) & E4210_MUX_HPM_MASK)
+ div1 = readl(base + E4210_DIV_CPU1) &
+ (E4210_DIV1_HPM_MASK | E4210_DIV1_COPY_MASK);
+ }
+
+ /*
+ * If the old parent clock speed is less than the clock speed of
+ * the alternate parent, then it should be ensured that at no point
+ * the armclk speed is more than the old_prate until the dividers are
+ * set. Also workaround the issue of the dividers being set to lower
+ * values before the parent clock speed is set to new lower speed
+ * (this can result in too high speed of armclk output clocks).
+ */
+ if (alt_prate > ndata->old_rate || ndata->old_rate > ndata->new_rate) {
+ unsigned long tmp_rate = min(ndata->old_rate, ndata->new_rate);
+
+ alt_div = DIV_ROUND_UP(alt_prate, tmp_rate) - 1;
+ WARN_ON(alt_div >= MAX_DIV);
+
+ if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
+ /*
+ * In Exynos4210, ATB clock parent is also mout_core. So
+ * ATB clock also needs to be mantained at safe speed.
+ */
+ alt_div |= E4210_DIV0_ATB_MASK;
+ alt_div_mask |= E4210_DIV0_ATB_MASK;
+ }
+ exynos_set_safe_div(base, alt_div, alt_div_mask);
+ div0 |= alt_div;
+ }
+
+ /* select sclk_mpll as the alternate parent */
+ mux_reg = readl(base + E4210_SRC_CPU);
+ writel(mux_reg | (1 << 16), base + E4210_SRC_CPU);
+ wait_until_mux_stable(base + E4210_STAT_CPU, 16, 2);
+
+ /* alternate parent is active now. set the dividers */
+ writel(div0, base + E4210_DIV_CPU0);
+ wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, DIV_MASK_ALL);
+
+ if (cpuclk->flags & CLK_CPU_HAS_DIV1) {
+ writel(div1, base + E4210_DIV_CPU1);
+ wait_until_divider_stable(base + E4210_DIV_STAT_CPU1,
+ DIV_MASK_ALL);
+ }
+
+ spin_unlock_irqrestore(cpuclk->lock, flags);
+ return 0;
+}
+
+/* handler for post-rate change notification from parent clock */
+static int exynos_cpuclk_post_rate_change(struct clk_notifier_data *ndata,
+ struct exynos_cpuclk *cpuclk, void __iomem *base)
+{
+ const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
+ unsigned long div = 0, div_mask = DIV_MASK;
+ unsigned long mux_reg;
+ unsigned long flags;
+
+ /* find out the divider values to use for clock data */
+ if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
+ while ((cfg_data->prate * 1000) != ndata->new_rate) {
+ if (cfg_data->prate == 0)
+ return -EINVAL;
+ cfg_data++;
+ }
+ }
+
+ spin_lock_irqsave(cpuclk->lock, flags);
+
+ /* select mout_apll as the alternate parent */
+ mux_reg = readl(base + E4210_SRC_CPU);
+ writel(mux_reg & ~(1 << 16), base + E4210_SRC_CPU);
+ wait_until_mux_stable(base + E4210_STAT_CPU, 16, 1);
+
+ if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
+ div |= (cfg_data->div0 & E4210_DIV0_ATB_MASK);
+ div_mask |= E4210_DIV0_ATB_MASK;
+ }
+
+ exynos_set_safe_div(base, div, div_mask);
+ spin_unlock_irqrestore(cpuclk->lock, flags);
+ return 0;
+}
+
+/*
+ * This notifier function is called for the pre-rate and post-rate change
+ * notifications of the parent clock of cpuclk.
+ */
+static int exynos_cpuclk_notifier_cb(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct clk_notifier_data *ndata = data;
+ struct exynos_cpuclk *cpuclk;
+ void __iomem *base;
+ int err = 0;
+
+ cpuclk = container_of(nb, struct exynos_cpuclk, clk_nb);
+ base = cpuclk->ctrl_base;
+
+ if (event == PRE_RATE_CHANGE)
+ err = exynos_cpuclk_pre_rate_change(ndata, cpuclk, base);
+ else if (event == POST_RATE_CHANGE)
+ err = exynos_cpuclk_post_rate_change(ndata, cpuclk, base);
+
+ return notifier_from_errno(err);
+}
+
+/* helper function to register a CPU clock */
+int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
+ unsigned int lookup_id, const char *name, const char *parent,
+ const char *alt_parent, unsigned long offset,
+ const struct exynos_cpuclk_cfg_data *cfg,
+ unsigned long num_cfgs, unsigned long flags)
+{
+ struct exynos_cpuclk *cpuclk;
+ struct clk_init_data init;
+ struct clk *clk;
+ int ret = 0;
+
+ cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
+ if (!cpuclk)
+ return -ENOMEM;
+
+ init.name = name;
+ init.flags = CLK_SET_RATE_PARENT;
+ init.parent_names = &parent;
+ init.num_parents = 1;
+ init.ops = &exynos_cpuclk_clk_ops;
+
+ cpuclk->hw.init = &init;
+ cpuclk->ctrl_base = ctx->reg_base + offset;
+ cpuclk->lock = &ctx->lock;
+ cpuclk->flags = flags;
+ cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb;
+
+ cpuclk->alt_parent = __clk_lookup(alt_parent);
+ if (!cpuclk->alt_parent) {
+ pr_err("%s: could not lookup alternate parent %s\n",
+ __func__, alt_parent);
+ ret = -EINVAL;
+ goto free_cpuclk;
+ }
+
+ clk = __clk_lookup(parent);
+ if (!clk) {
+ pr_err("%s: could not lookup parent clock %s\n",
+ __func__, parent);
+ ret = -EINVAL;
+ goto free_cpuclk;
+ }
+
+ ret = clk_notifier_register(clk, &cpuclk->clk_nb);
+ if (ret) {
+ pr_err("%s: failed to register clock notifier for %s\n",
+ __func__, name);
+ goto free_cpuclk;
+ }
+
+ cpuclk->cfg = kmemdup(cfg, sizeof(*cfg) * num_cfgs, GFP_KERNEL);
+ if (!cpuclk->cfg) {
+ pr_err("%s: could not allocate memory for cpuclk data\n",
+ __func__);
+ ret = -ENOMEM;
+ goto unregister_clk_nb;
+ }
+
+ clk = clk_register(NULL, &cpuclk->hw);
+ if (IS_ERR(clk)) {
+ pr_err("%s: could not register cpuclk %s\n", __func__, name);
+ ret = PTR_ERR(clk);
+ goto free_cpuclk_data;
+ }
+
+ samsung_clk_add_lookup(ctx, clk, lookup_id);
+ return 0;
+
+free_cpuclk_data:
+ kfree(cpuclk->cfg);
+unregister_clk_nb:
+ clk_notifier_unregister(__clk_lookup(parent), &cpuclk->clk_nb);
+free_cpuclk:
+ kfree(cpuclk);
+ return ret;
+}
Code Review / kvmfornfv.git / blobdiff