[PATCH 2/3] clk: samsung: cpu: prepare for adding Exynos5433 CPU clocks

Bartlomiej Zolnierkiewicz
2016-05-24T13:19:16Z

Exynos5433 uses different register layout for CPU clock registers
than earlier SoCs so add new code for handling this layout. Also
add new CLK_CPU_HAS_E5433_REGS_LAYOUT flag to request using it.

There should be no functional change resulting from this patch.

Cc: Kukjin Kim <kgene@kernel.org>
CC: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
drivers/clk/samsung/clk-cpu.c | 131 +++++++++++++++++++++++++++++++++++++++++-
drivers/clk/samsung/clk-cpu.h | 4 +-
2 files changed, 133 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/samsung/clk-cpu.c b/drivers/clk/samsung/clk-cpu.c
index 813003d..8bf7e80 100644
--- a/drivers/clk/samsung/clk-cpu.c
+++ b/drivers/clk/samsung/clk-cpu.c
@@ -45,6 +45,13 @@
#define E4210_DIV_STAT_CPU0 0x400
#define E4210_DIV_STAT_CPU1 0x404

+#define E5433_MUX_SEL2 0x008
+#define E5433_MUX_STAT2 0x208
+#define E5433_DIV_CPU0 0x400
+#define E5433_DIV_CPU1 0x404
+#define E5433_DIV_STAT_CPU0 0x500
+#define E5433_DIV_STAT_CPU1 0x504
+
#define E4210_DIV0_RATIO0_MASK 0x7
#define E4210_DIV1_HPM_MASK (0x7 << 4)
#define E4210_DIV1_COPY_MASK (0x7 << 0)
@@ -253,6 +260,102 @@ static int exynos_cpuclk_post_rate_change(struct clk_notifier_data *ndata,
}

/*
+ * 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 exynos5433_set_safe_div(void __iomem *base, unsigned long div,
+ unsigned long mask)
+{
+ unsigned long div0;
+
+ div0 = readl(base + E5433_DIV_CPU0);
+ div0 = (div0 & ~mask) | (div & mask);
+ writel(div0, base + E5433_DIV_CPU0);
+ wait_until_divider_stable(base + E5433_DIV_STAT_CPU0, mask);
+}
+
+/* handler for pre-rate change notification from parent clock */
+static int exynos5433_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.
+ */
+ div0 = cfg_data->div0;
+ div1 = cfg_data->div1;
+
+ /*
+ * 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);
+
+ exynos5433_set_safe_div(base, alt_div, alt_div_mask);
+ div0 |= alt_div;
+ }
+
+ /* select the alternate parent */
+ mux_reg = readl(base + E5433_MUX_SEL2);
+ writel(mux_reg | 1, base + E5433_MUX_SEL2);
+ wait_until_mux_stable(base + E5433_MUX_STAT2, 0, 2);
+
+ /* alternate parent is active now. set the dividers */
+ writel(div0, base + E5433_DIV_CPU0);
+ wait_until_divider_stable(base + E5433_DIV_STAT_CPU0, DIV_MASK_ALL);
+
+ writel(div1, base + E5433_DIV_CPU1);
+ wait_until_divider_stable(base + E5433_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 exynos5433_cpuclk_post_rate_change(struct clk_notifier_data *ndata,
+ struct exynos_cpuclk *cpuclk, void __iomem *base)
+{
+ unsigned long div = 0, div_mask = DIV_MASK;
+ unsigned long mux_reg;
+ unsigned long flags;
+
+ spin_lock_irqsave(cpuclk->lock, flags);
+
+ /* select apll as the alternate parent */
+ mux_reg = readl(base + E5433_MUX_SEL2);
+ writel(mux_reg & ~1, base + E5433_MUX_SEL2);
+ wait_until_mux_stable(base + E5433_MUX_STAT2, 0, 1);
+
+ exynos5433_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.
*/
@@ -275,6 +378,29 @@ static int exynos_cpuclk_notifier_cb(struct notifier_block *nb,
return notifier_from_errno(err);
}

+/*
+ * This notifier function is called for the pre-rate and post-rate change
+ * notifications of the parent clock of cpuclk.
+ */
+static int exynos5433_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 = exynos5433_cpuclk_pre_rate_change(ndata, cpuclk, base);
+ else if (event == POST_RATE_CHANGE)
+ err = exynos5433_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,
@@ -301,7 +427,10 @@ int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
cpuclk->ctrl_base = ctx->reg_base + offset;
cpuclk->lock = &ctx->lock;
cpuclk->flags = flags;
- cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb;
+ if (flags & CLK_CPU_HAS_E5433_REGS_LAYOUT)
+ cpuclk->clk_nb.notifier_call = exynos5433_cpuclk_notifier_cb;
+ else
+ cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb;

cpuclk->alt_parent = __clk_lookup(alt_parent);
if (!cpuclk->alt_parent) {
diff --git a/drivers/clk/samsung/clk-cpu.h b/drivers/clk/samsung/clk-cpu.h
index 37874d3..d4b6b51 100644
--- a/drivers/clk/samsung/clk-cpu.h
+++ b/drivers/clk/samsung/clk-cpu.h
@@ -57,10 +57,12 @@ struct exynos_cpuclk {
struct notifier_block clk_nb;
unsigned long flags;

-/* The CPU clock registers has DIV1 configuration register */
+/* The CPU clock registers have DIV1 configuration register */
#define CLK_CPU_HAS_DIV1 (1 << 0)
/* When ALT parent is active, debug clocks need safe divider values */
#define CLK_CPU_NEEDS_DEBUG_ALT_DIV (1 << 1)
+/* The CPU clock registers have Exynos5433-compatible layout */
+#define CLK_CPU_HAS_E5433_REGS_LAYOUT (1 << 2)
};

extern int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
--
1.9.1