From 2e33559f3d4f111f969a7e0da29a264f41bae86a Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Fri, 3 Feb 2012 15:13:54 +0000 Subject: [PATCH] tegra: Enhance clock support to handle 16-bit clock divisors I2C ports have a 16-bit clock divisor. Add code to handle this special case so that I2C speeds below 150KHz are supported. Signed-off-by: Simon Glass Signed-off-by: Tom Warren --- arch/arm/cpu/armv7/tegra2/clock.c | 63 ++++++++++++++-------- arch/arm/include/asm/arch-tegra2/clk_rst.h | 10 +++- 2 files changed, 49 insertions(+), 24 deletions(-) diff --git a/arch/arm/cpu/armv7/tegra2/clock.c b/arch/arm/cpu/armv7/tegra2/clock.c index a94cf817e5..39376ab86e 100644 --- a/arch/arm/cpu/armv7/tegra2/clock.c +++ b/arch/arm/cpu/armv7/tegra2/clock.c @@ -68,6 +68,7 @@ enum clock_type_id { CLOCK_TYPE_MCPT, CLOCK_TYPE_PCM, CLOCK_TYPE_PCMT, + CLOCK_TYPE_PCMT16, /* CLOCK_TYPE_PCMT with 16-bit divider */ CLOCK_TYPE_PCXTS, CLOCK_TYPE_PDCT, @@ -99,6 +100,7 @@ static enum clock_id clock_source[CLOCK_TYPE_COUNT][CLOCK_MAX_MUX] = { { CLK(MEMORY), CLK(CGENERAL), CLK(PERIPH), CLK(OSC) }, { CLK(PERIPH), CLK(CGENERAL), CLK(MEMORY), CLK(NONE) }, { CLK(PERIPH), CLK(CGENERAL), CLK(MEMORY), CLK(OSC) }, + { CLK(PERIPH), CLK(CGENERAL), CLK(MEMORY), CLK(OSC) }, { CLK(PERIPH), CLK(CGENERAL), CLK(XCPU), CLK(OSC) }, { CLK(PERIPH), CLK(DISPLAY), CLK(CGENERAL), CLK(OSC) }, }; @@ -212,8 +214,8 @@ static enum clock_type_id clock_periph_type[PERIPHC_COUNT] = { /* 0x08 */ TYPE(PERIPHC_XIO, CLOCK_TYPE_PCMT), - TYPE(PERIPHC_I2C1, CLOCK_TYPE_PCMT), - TYPE(PERIPHC_DVC_I2C, CLOCK_TYPE_PCMT), + TYPE(PERIPHC_I2C1, CLOCK_TYPE_PCMT16), + TYPE(PERIPHC_DVC_I2C, CLOCK_TYPE_PCMT16), TYPE(PERIPHC_TWC, CLOCK_TYPE_PCMT), TYPE(PERIPHC_NONE, CLOCK_TYPE_NONE), TYPE(PERIPHC_SPI1, CLOCK_TYPE_PCMT), @@ -247,7 +249,7 @@ static enum clock_type_id clock_periph_type[PERIPHC_COUNT] = { TYPE(PERIPHC_HDMI, CLOCK_TYPE_PDCT), TYPE(PERIPHC_NONE, CLOCK_TYPE_NONE), TYPE(PERIPHC_TVDAC, CLOCK_TYPE_PDCT), - TYPE(PERIPHC_I2C2, CLOCK_TYPE_PCMT), + TYPE(PERIPHC_I2C2, CLOCK_TYPE_PCMT16), TYPE(PERIPHC_EMC, CLOCK_TYPE_MCPT), /* 0x28 */ @@ -257,7 +259,7 @@ static enum clock_type_id clock_periph_type[PERIPHC_COUNT] = { TYPE(PERIPHC_NONE, CLOCK_TYPE_NONE), TYPE(PERIPHC_NONE, CLOCK_TYPE_NONE), TYPE(PERIPHC_SPI4, CLOCK_TYPE_PCMT), - TYPE(PERIPHC_I2C3, CLOCK_TYPE_PCMT), + TYPE(PERIPHC_I2C3, CLOCK_TYPE_PCMT16), TYPE(PERIPHC_SDMMC3, CLOCK_TYPE_PCMT), /* 0x30 */ @@ -519,14 +521,16 @@ void clock_ll_set_source(enum periph_id periph_id, unsigned source) * Given the parent's rate and the required rate for the children, this works * out the peripheral clock divider to use, in 7.1 binary format. * + * @param divider_bits number of divider bits (8 or 16) * @param parent_rate clock rate of parent clock in Hz * @param rate required clock rate for this clock * @return divider which should be used */ -static int clk_div7_1_get_divider(unsigned long parent_rate, - unsigned long rate) +static int clk_get_divider(unsigned divider_bits, unsigned long parent_rate, + unsigned long rate) { u64 divider = parent_rate * 2; + unsigned max_divider = 1 << divider_bits; divider += rate - 1; do_div(divider, rate); @@ -534,7 +538,7 @@ static int clk_div7_1_get_divider(unsigned long parent_rate, if ((s64)divider - 2 < 0) return 0; - if ((s64)divider - 2 > 255) + if ((s64)divider - 2 >= max_divider) return -1; return divider - 2; @@ -572,6 +576,7 @@ unsigned long clock_get_periph_rate(enum periph_id periph_id, * required child clock rate. This function assumes that a second-stage * divisor is available which can divide by powers of 2 from 1 to 256. * + * @param divider_bits number of divider bits (8 or 16) * @param parent_rate clock rate of parent clock in Hz * @param rate required clock rate for this clock * @param extra_div value for the second-stage divisor (not set if this @@ -579,8 +584,8 @@ unsigned long clock_get_periph_rate(enum periph_id periph_id, * @return divider which should be used, or -1 if nothing is valid * */ -static int find_best_divider(unsigned long parent_rate, unsigned long rate, - int *extra_div) +static int find_best_divider(unsigned divider_bits, unsigned long parent_rate, + unsigned long rate, int *extra_div) { int shift; int best_divider = -1; @@ -589,7 +594,8 @@ static int find_best_divider(unsigned long parent_rate, unsigned long rate, /* try dividers from 1 to 256 and find closest match */ for (shift = 0; shift <= 8 && best_error > 0; shift++) { unsigned divided_parent = parent_rate >> shift; - int divider = clk_div7_1_get_divider(divided_parent, rate); + int divider = clk_get_divider(divider_bits, divided_parent, + rate); unsigned effective_rate = get_rate_from_divider(divided_parent, divider); int error = rate - effective_rate; @@ -615,10 +621,11 @@ static int find_best_divider(unsigned long parent_rate, unsigned long rate, * @param periph_id peripheral to start * @param source PLL id of required parent clock * @param mux_bits Set to number of bits in mux register: 2 or 4 + * @param divider_bits Set to number of divider bits (8 or 16) * @return mux value (0-4, or -1 if not found) */ static int get_periph_clock_source(enum periph_id periph_id, - enum clock_id parent, int *mux_bits) + enum clock_id parent, int *mux_bits, int *divider_bits) { enum clock_type_id type; enum periphc_internal_id internal_id; @@ -632,11 +639,18 @@ static int get_periph_clock_source(enum periph_id periph_id, type = clock_periph_type[internal_id]; assert(clock_type_id_isvalid(type)); - /* Special case here for the clock with a 4-bit source mux */ + /* + * Special cases here for the clock with a 4-bit source mux and I2C + * with its 16-bit divisor + */ if (type == CLOCK_TYPE_PCXTS) *mux_bits = 4; else *mux_bits = 2; + if (type == CLOCK_TYPE_PCMT16) + *divider_bits = 16; + else + *divider_bits = 8; for (mux = 0; mux < CLOCK_MAX_MUX; mux++) if (clock_source[type][mux] == parent) @@ -662,24 +676,22 @@ static int get_periph_clock_source(enum periph_id periph_id, * Adjust peripheral PLL to use the given divider and source. * * @param periph_id peripheral to adjust - * @param parent Required parent clock (for source mux) - * @param divider Required divider in 7.1 format + * @param source Source number (0-3 or 0-7) + * @param mux_bits Number of mux bits (2 or 4) + * @param divider Required divider in 7.1 or 15.1 format * @return 0 if ok, -1 on error (requesting a parent clock which is not valid * for this peripheral) */ -static int adjust_periph_pll(enum periph_id periph_id, - enum clock_id parent, unsigned divider) +static int adjust_periph_pll(enum periph_id periph_id, int source, + int mux_bits, unsigned divider) { u32 *reg = get_periph_source_reg(periph_id); - unsigned source; - int mux_bits; clrsetbits_le32(reg, OUT_CLK_DIVISOR_MASK, divider << OUT_CLK_DIVISOR_SHIFT); udelay(1); /* work out the source clock and set it */ - source = get_periph_clock_source(periph_id, parent, &mux_bits); if (source < 0) return -1; if (mux_bits == 4) { @@ -697,14 +709,21 @@ unsigned clock_adjust_periph_pll_div(enum periph_id periph_id, enum clock_id parent, unsigned rate, int *extra_div) { unsigned effective_rate; + int mux_bits, divider_bits, source; int divider; + /* work out the source clock and set it */ + source = get_periph_clock_source(periph_id, parent, &mux_bits, + ÷r_bits); + if (extra_div) - divider = find_best_divider(pll_rate[parent], rate, extra_div); + divider = find_best_divider(divider_bits, pll_rate[parent], + rate, extra_div); else - divider = clk_div7_1_get_divider(pll_rate[parent], rate); + divider = clk_get_divider(divider_bits, pll_rate[parent], + rate); assert(divider >= 0); - if (adjust_periph_pll(periph_id, parent, divider)) + if (adjust_periph_pll(periph_id, source, mux_bits, divider)) return -1U; debug("periph %d, rate=%d, reg=%p = %x\n", periph_id, rate, get_periph_source_reg(periph_id), diff --git a/arch/arm/include/asm/arch-tegra2/clk_rst.h b/arch/arm/include/asm/arch-tegra2/clk_rst.h index 0b6e004fbc..415e420012 100644 --- a/arch/arm/include/asm/arch-tegra2/clk_rst.h +++ b/arch/arm/include/asm/arch-tegra2/clk_rst.h @@ -125,9 +125,15 @@ struct clk_rst_ctlr { #define OSC_FREQ_SHIFT 30 #define OSC_FREQ_MASK (3U << OSC_FREQ_SHIFT) -/* CLK_RST_CONTROLLER_CLK_SOURCE_x_OUT_0 */ +/* + * CLK_RST_CONTROLLER_CLK_SOURCE_x_OUT_0 - the mask here is normally 8 bits + * but can be 16. We could use knowledge we have to restrict the mask in + * the 8-bit cases (the divider_bits value returned by + * get_periph_clock_source()) but it does not seem worth it since the code + * already checks the ranges of values it is writing, in clk_get_divider(). + */ #define OUT_CLK_DIVISOR_SHIFT 0 -#define OUT_CLK_DIVISOR_MASK (255 << OUT_CLK_DIVISOR_SHIFT) +#define OUT_CLK_DIVISOR_MASK (0xffff << OUT_CLK_DIVISOR_SHIFT) #define OUT_CLK_SOURCE_SHIFT 30 #define OUT_CLK_SOURCE_MASK (3U << OUT_CLK_SOURCE_SHIFT) -- 2.25.1