diff options
Diffstat (limited to 'drivers/clk/renesas/rcar-gen3-cpg.c')
| -rw-r--r-- | drivers/clk/renesas/rcar-gen3-cpg.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/clk/renesas/rcar-gen3-cpg.c b/drivers/clk/renesas/rcar-gen3-cpg.c index 0904886f5501..628b63b85d3f 100644 --- a/drivers/clk/renesas/rcar-gen3-cpg.c +++ b/drivers/clk/renesas/rcar-gen3-cpg.c @@ -13,6 +13,7 @@ */ #include <linux/bug.h> +#include <linux/bitfield.h> #include <linux/clk.h> #include <linux/clk-provider.h> #include <linux/device.h> @@ -62,6 +63,140 @@ static void cpg_simple_notifier_register(struct raw_notifier_head *notifiers, } /* + * Z Clock & Z2 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 ) / 2 + * 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 GENMASK(12, 8) +#define CPG_FRQCRC_Z2FC_MASK GENMASK(4, 0) + +struct cpg_z_clk { + struct clk_hw hw; + void __iomem *reg; + void __iomem *kick_reg; + unsigned long mask; +}; + +#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; + u32 val; + + val = readl(zclk->reg) & zclk->mask; + mult = 32 - (val >> __ffs(zclk->mask)); + + /* Factor of 2 is for fixed divider */ + return DIV_ROUND_CLOSEST_ULL((u64)parent_rate * mult, 32 * 2); +} + +static long cpg_z_clk_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + /* Factor of 2 is for fixed divider */ + unsigned long prate = *parent_rate / 2; + unsigned int mult; + + mult = div_u64(rate * 32ULL, prate); + mult = clamp(mult, 1U, 32U); + + return (u64)prate * mult / 32; +} + +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; + unsigned int i; + u32 val, kick; + + /* Factor of 2 is for fixed divider */ + mult = DIV_ROUND_CLOSEST_ULL(rate * 32ULL * 2, parent_rate); + mult = clamp(mult, 1U, 32U); + + if (readl(zclk->kick_reg) & CPG_FRQCRB_KICK) + return -EBUSY; + + val = readl(zclk->reg) & ~zclk->mask; + val |= ((32 - mult) << __ffs(zclk->mask)) & zclk->mask; + writel(val, zclk->reg); + + /* + * Set KICK bit in FRQCRB to update hardware setting and wait for + * clock change completion. + */ + kick = readl(zclk->kick_reg); + kick |= CPG_FRQCRB_KICK; + 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 (!(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, + unsigned long mask) +{ + 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; + zclk->mask = mask; + + clk = clk_register(NULL, &zclk->hw); + if (IS_ERR(clk)) + kfree(zclk); + + return clk; +} + +/* * SDn Clock */ #define CPG_SD_STP_HCK BIT(9) @@ -420,6 +555,14 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev, mult = 1; break; + case CLK_TYPE_GEN3_Z: + return cpg_z_clk_register(core->name, __clk_get_name(parent), + base, CPG_FRQCRC_ZFC_MASK); + + case CLK_TYPE_GEN3_Z2: + return cpg_z_clk_register(core->name, __clk_get_name(parent), + base, CPG_FRQCRC_Z2FC_MASK); + default: return ERR_PTR(-EINVAL); } |