[PATCH 2/2] ARM: shmobile: r8a73a4: implement CPU clock scaling for CPUFreq
Guennadi Liakhovetski
g.liakhovetski at gmx.de
Wed May 22 05:12:37 EDT 2013
This patch adds support for the Z-clock on r8a73a4 SoCs, which is driving
the Cortex A15 core, and a "cpufreq-cpu0" platform device. Adding an
"operating-points" property to the CPU0 DT node and a regulator, this
patch allows platforms to use the generic cpufreq-cpu0 driver to use
SoC's DVFS capabilities.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas at gmail.com>
---
arch/arm/mach-shmobile/Kconfig | 2 +
arch/arm/mach-shmobile/clock-r8a73a4.c | 123 +++++++++++++++++++++++++++++++-
arch/arm/mach-shmobile/setup-r8a73a4.c | 1 +
3 files changed, 125 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-shmobile/Kconfig b/arch/arm/mach-shmobile/Kconfig
index 97bc6cf..ec349ad 100644
--- a/arch/arm/mach-shmobile/Kconfig
+++ b/arch/arm/mach-shmobile/Kconfig
@@ -26,6 +26,8 @@ config ARCH_R8A73A4
select ARM_ARCH_TIMER
select SH_CLK_CPG
select RENESAS_IRQC
+ select ARCH_HAS_CPUFREQ
+ select ARCH_HAS_OPP
config ARCH_R8A7740
bool "R-Mobile A1 (R8A77400)"
diff --git a/arch/arm/mach-shmobile/clock-r8a73a4.c b/arch/arm/mach-shmobile/clock-r8a73a4.c
index d5176d0..824789c 100644
--- a/arch/arm/mach-shmobile/clock-r8a73a4.c
+++ b/arch/arm/mach-shmobile/clock-r8a73a4.c
@@ -34,6 +34,7 @@
#define FRQCRA 0xE6150000
#define FRQCRB 0xE6150004
+#define FRQCRC 0xE61500E0
#define VCLKCR1 0xE6150008
#define VCLKCR2 0xE615000C
#define VCLKCR3 0xE615001C
@@ -52,6 +53,7 @@
#define HSICKCR 0xE615026C
#define M4CKCR 0xE6150098
#define PLLECR 0xE61500D0
+#define PLL0CR 0xE61500D8
#define PLL1CR 0xE6150028
#define PLL2CR 0xE615002C
#define PLL2SCR 0xE61501F4
@@ -177,6 +179,7 @@ static struct sh_clk_ops pll_clk_ops = {
.mapping = &cpg_mapping, \
}
+PLL_CLOCK(pll0_clk, &main_clk, pll_parent_main, 1, 20, PLL0CR, 0);
PLL_CLOCK(pll1_clk, &main_clk, pll_parent_main, 1, 7, PLL1CR, 1);
PLL_CLOCK(pll2_clk, &main_div2_clk, pll_parent_main_extal, 3, 5, PLL2CR, 2);
PLL_CLOCK(pll2s_clk, &main_div2_clk, pll_parent_main_extal, 3, 5, PLL2SCR, 4);
@@ -184,6 +187,14 @@ PLL_CLOCK(pll2h_clk, &main_div2_clk, pll_parent_main_extal, 3, 5, PLL2HCR, 5);
SH_FIXED_RATIO_CLK(pll1_div2_clk, pll1_clk, div2);
+static atomic_t frqcr_lock;
+
+/* Several clocks need to access FRQCRB, have to lock */
+static bool frqcr_kick_check(struct clk *clk)
+{
+ return !(ioread32(CPG_MAP(FRQCRB)) & BIT(31));
+}
+
static int frqcr_kick_do(struct clk *clk)
{
int i;
@@ -199,6 +210,107 @@ static int frqcr_kick_do(struct clk *clk)
return -ETIMEDOUT;
}
+static int zclk_set_rate(struct clk *clk, unsigned long rate)
+{
+ void __iomem *frqcrc;
+ int ret;
+ unsigned long step, p_rate;
+ u32 val;
+
+ if (!clk->parent || !__clk_get(clk->parent))
+ return -ENODEV;
+
+ if (!atomic_inc_and_test(&frqcr_lock) || !frqcr_kick_check(clk)) {
+ ret = -EBUSY;
+ goto done;
+ }
+
+ frqcrc = clk->mapped_reg + (FRQCRC - (u32)clk->enable_reg);
+
+ p_rate = clk_get_rate(clk->parent);
+ if (rate == p_rate) {
+ val = 0;
+ } else {
+ step = DIV_ROUND_CLOSEST(p_rate, 32);
+ val = 32 - rate / step;
+ }
+
+ iowrite32((ioread32(frqcrc) & ~(clk->div_mask << clk->enable_bit)) |
+ (val << clk->enable_bit), frqcrc);
+
+ ret = frqcr_kick_do(clk);
+
+done:
+ atomic_dec(&frqcr_lock);
+ __clk_put(clk->parent);
+ return ret;
+}
+
+static long zclk_round_rate(struct clk *clk, unsigned long rate)
+{
+ /*
+ * theoretical rate = parent rate * multiplier / 32,
+ * where 1 <= multiplier <= 32. Therefore we should do
+ * multiplier = rate * 32 / parent rate
+ * rounded rate = parent rate * multiplier / 32.
+ * However, multiplication before division won't fit in 32 bits, so
+ * we sacrifice some precision by first dividing and then multiplying.
+ * To find the nearest divisor we calculate both and pick up the best
+ * one. This avoids 64-bit arithmetics.
+ */
+ unsigned long step, mul_min, mul_max, rate_min, rate_max;
+
+ rate_max = clk_get_rate(clk->parent);
+
+ /* output freq <= parent */
+ if (rate >= rate_max)
+ return rate_max;
+
+ step = DIV_ROUND_CLOSEST(rate_max, 32);
+ /* output freq >= parent / 32 */
+ if (step >= rate)
+ return step;
+
+ mul_min = rate / step;
+ mul_max = DIV_ROUND_UP(rate, step);
+ rate_min = step * mul_min;
+ if (mul_max == mul_min)
+ return rate_min;
+
+ rate_max = step * mul_max;
+
+ if (rate_max - rate < rate - rate_min)
+ return rate_max;
+
+ return rate_min;
+}
+
+static unsigned long zclk_recalc(struct clk *clk)
+{
+ void __iomem *frqcrc = FRQCRC - (u32)clk->enable_reg + clk->mapped_reg;
+ unsigned int max = clk->div_mask + 1;
+ unsigned long val = ((ioread32(frqcrc) >> clk->enable_bit) &
+ clk->div_mask);
+
+ return DIV_ROUND_CLOSEST(clk_get_rate(clk->parent), max) *
+ (max - val);
+}
+
+static struct sh_clk_ops zclk_ops = {
+ .recalc = zclk_recalc,
+ .set_rate = zclk_set_rate,
+ .round_rate = zclk_round_rate,
+};
+
+static struct clk z_clk = {
+ .parent = &pll0_clk,
+ .div_mask = 0x1f,
+ .enable_bit = 8,
+ /* We'll need to access FRQCRB and FRQCRC */
+ .enable_reg = (void __iomem *)FRQCRB,
+ .ops = &zclk_ops,
+};
+
static struct clk *main_clks[] = {
&extalr_clk,
&extal1_clk,
@@ -210,17 +322,21 @@ static struct clk *main_clks[] = {
&main_div2_clk,
&fsiack_clk,
&fsibck_clk,
+ &pll0_clk,
&pll1_clk,
&pll1_div2_clk,
&pll2_clk,
&pll2s_clk,
&pll2h_clk,
+ &z_clk,
};
/* DIV4 */
static void div4_kick(struct clk *clk)
{
- frqcr_kick_do(clk);
+ if (!WARN(!atomic_inc_and_test(&frqcr_lock), "FRQCR* lock broken!\n"))
+ frqcr_kick_do(clk);
+ atomic_dec(&frqcr_lock);
}
static int divisors[] = { 2, 3, 4, 6, 8, 12, 16, 18, 24, 0, 36, 48, 10};
@@ -396,6 +512,9 @@ static struct clk_lookup lookups[] = {
CLKDEV_CON_ID("pll2s", &pll2s_clk),
CLKDEV_CON_ID("pll2h", &pll2h_clk),
+ /* CPU clock */
+ CLKDEV_DEV_ID("cpufreq-cpu0", &z_clk),
+
/* DIV6 */
CLKDEV_CON_ID("zb", &div6_clks[DIV6_ZB]),
CLKDEV_CON_ID("vck1", &div6_clks[DIV6_VCK1]),
@@ -439,6 +558,8 @@ void __init r8a73a4_clock_init(void)
int k, ret = 0;
u32 ckscr;
+ atomic_set(&frqcr_lock, -1);
+
reg = ioremap_nocache(CKSCR, PAGE_SIZE);
BUG_ON(!reg);
ckscr = ioread32(reg);
diff --git a/arch/arm/mach-shmobile/setup-r8a73a4.c b/arch/arm/mach-shmobile/setup-r8a73a4.c
index c5a75a7..7265e14 100644
--- a/arch/arm/mach-shmobile/setup-r8a73a4.c
+++ b/arch/arm/mach-shmobile/setup-r8a73a4.c
@@ -185,6 +185,7 @@ void __init r8a73a4_add_standard_devices(void)
#ifdef CONFIG_USE_OF
void __init r8a73a4_add_standard_devices_dt(void)
{
+ platform_device_register_simple("cpufreq-cpu0", -1, NULL, 0);
of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
}
--
1.7.2.5
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