clk: renesas: rcar-gen3: Add Z clock divider support

Message ID	1492624001-3758-1-git-send-email-ykaneko0929@gmail.com (mailing list archive)
State	Superseded, archived
Delegated to:	Stephen Boyd
Headers	show Return-Path: <linux-clk-owner@kernel.org> From: Yoshihiro Kaneko <ykaneko0929@gmail.com> To: linux-clk@vger.kernel.org Cc: Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@codeaurora.org>, Geert Uytterhoeven <geert+renesas@glider.be>, Simon Horman <horms@verge.net.au>, Magnus Damm <magnus.damm@gmail.com>, linux-renesas-soc@vger.kernel.org Subject: [PATCH] clk: renesas: rcar-gen3: Add Z clock divider support Date: Thu, 20 Apr 2017 02:46:21 +0900 Message-Id: <1492624001-3758-1-git-send-email-ykaneko0929@gmail.com> Sender: linux-clk-owner@vger.kernel.org Precedence: bulk

diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c index 3dee900..8419f27 100644 --- a/drivers/clk/renesas/rcar-gen3-cpg.c +++ b/drivers/clk/renesas/rcar-gen3-cpg.c @@ -29,6 +29,145 @@ #define CPG_PLL2CR 0x002c #define CPG_PLL4CR 0x01f4 +/** Modify for Z-clock + * ----------------------------------------------------------------------------- + * Z Clock + * + * Traits of this clock: + * prepare - clk_prepare only ensures that parents are prepared + * enable - clk_enable only ensures that parents are enabled + * rate - rate is adjustable. clk->rate = parent->rate * mult / 32 + * parent - fixed parent. No clk_set_parent support + */ +#define CPG_FRQCRB 0x00000004 +#define CPG_FRQCRB_KICK BIT(31) +#define CPG_FRQCRC 0x000000e0 +#define CPG_FRQCRC_ZFC_MASK (0x1f << 8) +#define CPG_FRQCRC_ZFC_SHIFT 8 + + +struct cpg_z_clk { + struct clk_hw hw; + void __iomem *reg; + void __iomem *kick_reg; +}; + +#define to_z_clk(_hw) container_of(_hw, struct cpg_z_clk, hw) + +static unsigned long cpg_z_clk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct cpg_z_clk *zclk = to_z_clk(hw); + unsigned int mult; + unsigned int val; + unsigned long rate; + + val = (clk_readl(zclk->reg) & CPG_FRQCRC_ZFC_MASK) + >> CPG_FRQCRC_ZFC_SHIFT; + mult = 32 - val; + + rate = div_u64((u64)parent_rate * mult + 16, 32); + /* Round to closest value at 100MHz unit */ + rate = 100000000*DIV_ROUND_CLOSEST(rate, 100000000); + return rate; +} + +static long cpg_z_clk_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + unsigned long prate = *parent_rate; + unsigned int mult; + + if (!prate) + prate = 1; + + mult = div_u64((u64)rate * 32 + prate/2, prate); + mult = clamp(mult, 1U, 32U); + + return *parent_rate / 32 * mult; +} + +static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct cpg_z_clk *zclk = to_z_clk(hw); + unsigned int mult; + u32 val, kick; + unsigned int i; + + mult = div_u64((u64)rate * 32 + parent_rate/2, parent_rate); + mult = clamp(mult, 1U, 32U); + + if (clk_readl(zclk->kick_reg) & CPG_FRQCRB_KICK) + return -EBUSY; + + val = clk_readl(zclk->reg); + val &= ~CPG_FRQCRC_ZFC_MASK; + val |= (32 - mult) << CPG_FRQCRC_ZFC_SHIFT; + clk_writel(val, zclk->reg); + + /* + * Set KICK bit in FRQCRB to update hardware setting and wait for + * clock change completion. + */ + kick = clk_readl(zclk->kick_reg); + kick |= CPG_FRQCRB_KICK; + clk_writel(kick, zclk->kick_reg); + + /* + * Note: There is no HW information about the worst case latency. + * + * Using experimental measurements, it seems that no more than + * ~10 iterations are needed, independently of the CPU rate. + * Since this value might be dependent of external xtal rate, pll1 + * rate or even the other emulation clocks rate, use 1000 as a + * "super" safe value. + */ + for (i = 1000; i; i--) { + if (!(clk_readl(zclk->kick_reg) & CPG_FRQCRB_KICK)) + return 0; + + cpu_relax(); + } + + return -ETIMEDOUT; +} + +static const struct clk_ops cpg_z_clk_ops = { + .recalc_rate = cpg_z_clk_recalc_rate, + .round_rate = cpg_z_clk_round_rate, + .set_rate = cpg_z_clk_set_rate, +}; + +static struct clk * __init cpg_z_clk_register(const char *name, + const char *parent_name, + void __iomem *reg) +{ + struct clk_init_data init; + struct cpg_z_clk *zclk; + struct clk *clk; + + zclk = kzalloc(sizeof(*zclk), GFP_KERNEL); + if (!zclk) + return ERR_PTR(-ENOMEM); + + init.name = name; + init.ops = &cpg_z_clk_ops; + init.flags = 0; + init.parent_names = &parent_name; + init.num_parents = 1; + + zclk->reg = reg + CPG_FRQCRC; + zclk->kick_reg = reg + CPG_FRQCRB; + zclk->hw.init = &init; + + clk = clk_register(NULL, &zclk->hw); + if (IS_ERR(clk)) + kfree(zclk); + + return clk; +} +/** End of modifying for Z-clock */ /* * SDn Clock @@ -360,6 +499,10 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev, parent = clks[cpg_clk_extalr]; break; + case CLK_TYPE_GEN3_Z: + return cpg_z_clk_register(core->name, __clk_get_name(parent), + base); + default: return ERR_PTR(-EINVAL); } diff --git a/drivers/clk/renesas/rcar-gen3-cpg.h b/drivers/clk/renesas/rcar-gen3-cpg.h index 073be54..b1e883d 100644 --- a/drivers/clk/renesas/rcar-gen3-cpg.h +++ b/drivers/clk/renesas/rcar-gen3-cpg.h @@ -20,6 +20,7 @@ enum rcar_gen3_clk_types { CLK_TYPE_GEN3_PLL4, CLK_TYPE_GEN3_SD, CLK_TYPE_GEN3_R, + CLK_TYPE_GEN3_Z, }; #define DEF_GEN3_SD(_name, _id, _parent, _offset) \

clk: renesas: rcar-gen3: Add Z clock divider support

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