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Date: Wed, 25 Sep 2013 13:58:04 +0900
From: Simon Horman <horms@...ge.net.au>
To: Guennadi Liakhovetski <g.liakhovetski@....de>
Cc: linux-kernel@...r.kernel.org, Magnus Damm <magnus.damm@...il.com>,
linux-sh@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
Guennadi Liakhovetski <g.liakhovetski+renesas@...il.com>
Subject: Re: [PATCH 3/4] ARM: shmobile: r8a7790: add CPUFreq clock support
On Mon, Sep 09, 2013 at 06:03:55PM +0200, Guennadi Liakhovetski wrote:
> Add support for the Z clock on r8a7790, driving the four SoC's CA15 cores,
> and its parent - PLL0. This is required for CPUFreq support on this SoC.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@...il.com>
Magnus, I think this needs a review from you.
> ---
> arch/arm/mach-shmobile/Kconfig | 2 +
> arch/arm/mach-shmobile/clock-r8a7790.c | 150 ++++++++++++++++++++++++++++++++
> 2 files changed, 152 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mach-shmobile/Kconfig b/arch/arm/mach-shmobile/Kconfig
> index 1f94c31..b9422f2 100644
> --- a/arch/arm/mach-shmobile/Kconfig
> +++ b/arch/arm/mach-shmobile/Kconfig
> @@ -100,6 +100,8 @@ config ARCH_R8A7790
> select CPU_V7
> select SH_CLK_CPG
> select RENESAS_IRQC
> + select ARCH_HAS_CPUFREQ
> + select ARCH_HAS_OPP
>
> config ARCH_EMEV2
> bool "Emma Mobile EV2"
> diff --git a/arch/arm/mach-shmobile/clock-r8a7790.c b/arch/arm/mach-shmobile/clock-r8a7790.c
> index 8e5e90b..3ef043e 100644
> --- a/arch/arm/mach-shmobile/clock-r8a7790.c
> +++ b/arch/arm/mach-shmobile/clock-r8a7790.c
> @@ -54,9 +54,12 @@
> #define SMSTPCR8 0xe6150990
> #define SMSTPCR9 0xe6150994
>
> +#define FRQCRB 0xE6150004
> #define SDCKCR 0xE6150074
> #define SD2CKCR 0xE6150078
> #define SD3CKCR 0xE615007C
> +#define FRQCRC 0xE61500E0
> +#define PLLECR 0xE61500D0
> #define MMC0CKCR 0xE6150240
> #define MMC1CKCR 0xE6150244
> #define SSPCKCR 0xE6150248
> @@ -85,6 +88,7 @@ static struct clk main_clk = {
> * clock ratio of these clock will be updated
> * on r8a7790_clock_init()
> */
> +SH_FIXED_RATIO_CLK_SET(pll0_clk, main_clk, 1, 1);
> SH_FIXED_RATIO_CLK_SET(pll1_clk, main_clk, 1, 1);
> SH_FIXED_RATIO_CLK_SET(pll3_clk, main_clk, 1, 1);
> SH_FIXED_RATIO_CLK_SET(lb_clk, pll1_clk, 1, 1);
> @@ -113,15 +117,155 @@ SH_FIXED_RATIO_CLK_SET(zb3d2_clk, pll3_clk, 1, 8);
> SH_FIXED_RATIO_CLK_SET(ddr_clk, pll3_clk, 1, 8);
> SH_FIXED_RATIO_CLK_SET(mp_clk, pll1_div2_clk, 1, 15);
>
> +/* Locking not needed yet, only one clock is using FRQCR[BC] divisors so far */
> +static atomic_t frqcr_lock;
> +#define CPG_MAP(o) ((o) - CPG_BASE + cpg_mapping.base)
> +
> +/* 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;
> +
> + /* set KICK bit in FRQCRB to update hardware setting, check success */
> + iowrite32(ioread32(CPG_MAP(FRQCRB)) | BIT(31), CPG_MAP(FRQCRB));
> + for (i = 1000; i; i--)
> + if (ioread32(CPG_MAP(FRQCRB)) & BIT(31))
> + cpu_relax();
> + else
> + return 0;
> +
> + 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;
> + }
> +
> + /*
> + * Users are supposed to first call clk_set_rate() only with
> + * clk_round_rate() results. So, we don't fix wrong rates here, but
> + * guard against them anyway
> + */
> +
> + p_rate = clk_get_rate(clk->parent);
> + if (rate == p_rate) {
> + val = 0;
> + } else {
> + step = DIV_ROUND_CLOSEST(p_rate, 32);
> +
> + if (rate > p_rate || rate < step) {
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + val = 32 - rate / step;
> + }
> +
> + frqcrc = clk->mapped_reg + (FRQCRC - (u32)clk->enable_reg);
> +
> + 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[] = {
> &extal_clk,
> &extal_div2_clk,
> &main_clk,
> + &pll0_clk,
> &pll1_clk,
> &pll1_div2_clk,
> &pll3_clk,
> &lb_clk,
> &qspi_clk,
> + &z_clk,
> &zg_clk,
> &zx_clk,
> &zs_clk,
> @@ -249,6 +393,9 @@ static struct clk_lookup lookups[] = {
> CLKDEV_CON_ID("qspi", &qspi_clk),
> CLKDEV_CON_ID("cp", &cp_clk),
>
> + /* CPU clock */
> + CLKDEV_DEV_ID("cpufreq-cpu0", &z_clk),
> +
> /* DIV4 */
> CLKDEV_CON_ID("sdh", &div4_clks[DIV4_SDH]),
>
> @@ -291,6 +438,7 @@ static struct clk_lookup lookups[] = {
> #define R8A7790_CLOCK_ROOT(e, m, p0, p1, p30, p31) \
> extal_clk.rate = e * 1000 * 1000; \
> main_clk.parent = m; \
> + SH_CLK_SET_RATIO(&pll0_clk_ratio, p0 / 2, 1); \
> SH_CLK_SET_RATIO(&pll1_clk_ratio, p1 / 2, 1); \
> if (mode & MD(19)) \
> SH_CLK_SET_RATIO(&pll3_clk_ratio, p31, 1); \
> @@ -303,6 +451,8 @@ void __init r8a7790_clock_init(void)
> u32 mode = r8a7790_read_mode_pins();
> int k, ret = 0;
>
> + atomic_set(&frqcr_lock, -1);
> +
> switch (mode & (MD(14) | MD(13))) {
> case 0:
> R8A7790_CLOCK_ROOT(15, &extal_clk, 172, 208, 106, 88);
> --
> 1.7.2.5
>
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