Simon, > -----Original Message----- > From: Simon Glass [mailto:sjg@xxxxxxxxxxxx] > Sent: Friday, February 03, 2012 6:14 PM > To: U-Boot Mailing List > Cc: Tom Warren; Stephen Warren; linux-tegra@xxxxxxxxxxxxxxx; Simon Glass > Subject: [PATCH v3 3/9] 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 <sjg@xxxxxxxxxxxx> > --- > Changes in v3: > - Add new patch to support 16-bit clock divisors required by I2C > > 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 11d2346..e58cb3b 100644 > --- a/arch/arm/cpu/armv7/tegra2/clock.c > +++ b/arch/arm/cpu/armv7/tegra2/clock.c > @@ -67,6 +67,7 @@ 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, > > @@ -98,6 +99,7 @@ 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) > }, > }; > @@ -211,8 +213,8 @@ 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), > @@ -246,7 +248,7 @@ 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 */ > @@ -256,7 +258,7 @@ 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 */ > @@ -518,14 +520,16 @@ 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); > @@ -533,7 +537,7 @@ 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; > @@ -571,6 +575,7 @@ 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 > @@ -578,8 +583,8 @@ 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; > @@ -588,7 +593,8 @@ 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; > @@ -614,10 +620,11 @@ 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; > @@ -631,11 +638,18 @@ 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) @@ -661,24 +675,22 @@ > 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) { > @@ -696,14 +708,21 @@ 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 0b6e004..415e420 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) > -- > 1.7.7.3 This looks reasonable from what I can see looking at the TRM for the CAR controller, so: Acked-by: Tom Warren <twarren@xxxxxxxxxx> Tom -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
