| Message ID | 20210418145655.10415-6-dariobin@libero.it |
|---|---|
| State | Superseded |
| Headers | show |
| Series | clk: ti: add am33xx spread spectrum clock support | expand |
On 18/04/2021 17:56, Dario Binacchi wrote: > The patch enables spread spectrum clocking (SSC) for MPU and LCD PLLs. > As reported by the TI spruh73x/spruhl7x RM, SSC is only supported for > the DISP/LCD and MPU PLLs on am33xx/am43xx. SSC is not supported for > DDR, PER, and CORE PLLs. > > Calculating the required values and setting the registers accordingly > was taken from the set_mpu_spreadspectrum routine contained in the > arch/arm/mach-omap2/am33xx/clock_am33xx.c file of the u-boot project. > > In locked condition, DPLL output clock = CLKINP *[M/N]. In case of > SSC enabled, the reference manual explains that there is a restriction > of range of M values. Since the omap2_dpll_round_rate routine attempts > to select the minimum possible N, the value of M obtained is not > guaranteed to be within the range required. With the new "ti,min-div" > parameter it is possible to increase N and consequently M to satisfy the > constraint imposed by SSC. > > Signed-off-by: Dario Binacchi <dariobin@libero.it> Reviewed-by: Tero Kristo <kristo@kernel.org> > > --- > > Changes in v5: > - Remove ssc_ack_mask field from dpll_data structure. It was not used. > - Change ssc_downspread type from u8 to bool in dpll_data structure. > > Changes in v4: > - Update commit message. > > Changes in v3: > - Use "ti,ssc-modfreq-hz" binding instead of "ti,ssc-modfreq". > > Changes in v2: > - Move the DT changes to the previous patch in the series. > > drivers/clk/ti/dpll.c | 39 ++++++++++++++++++ > drivers/clk/ti/dpll3xxx.c | 85 +++++++++++++++++++++++++++++++++++++++ > include/linux/clk/ti.h | 22 ++++++++++ > 3 files changed, 146 insertions(+) > > diff --git a/drivers/clk/ti/dpll.c b/drivers/clk/ti/dpll.c > index d6f1ac5b53e1..e9f9aee936ae 100644 > --- a/drivers/clk/ti/dpll.c > +++ b/drivers/clk/ti/dpll.c > @@ -290,7 +290,9 @@ static void __init of_ti_dpll_setup(struct device_node *node, > struct clk_init_data *init = NULL; > const char **parent_names = NULL; > struct dpll_data *dd = NULL; > + int ssc_clk_index; > u8 dpll_mode = 0; > + u32 min_div; > > dd = kmemdup(ddt, sizeof(*dd), GFP_KERNEL); > clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL); > @@ -345,6 +347,27 @@ static void __init of_ti_dpll_setup(struct device_node *node, > if (dd->autoidle_mask) { > if (ti_clk_get_reg_addr(node, 3, &dd->autoidle_reg)) > goto cleanup; > + > + ssc_clk_index = 4; > + } else { > + ssc_clk_index = 3; > + } > + > + if (dd->ssc_deltam_int_mask && dd->ssc_deltam_frac_mask && > + dd->ssc_modfreq_mant_mask && dd->ssc_modfreq_exp_mask) { > + if (ti_clk_get_reg_addr(node, ssc_clk_index++, > + &dd->ssc_deltam_reg)) > + goto cleanup; > + > + if (ti_clk_get_reg_addr(node, ssc_clk_index++, > + &dd->ssc_modfreq_reg)) > + goto cleanup; > + > + of_property_read_u32(node, "ti,ssc-modfreq-hz", > + &dd->ssc_modfreq); > + of_property_read_u32(node, "ti,ssc-deltam", &dd->ssc_deltam); > + dd->ssc_downspread = > + of_property_read_bool(node, "ti,ssc-downspread"); > } > > if (of_property_read_bool(node, "ti,low-power-stop")) > @@ -356,6 +379,10 @@ static void __init of_ti_dpll_setup(struct device_node *node, > if (of_property_read_bool(node, "ti,lock")) > dpll_mode |= 1 << DPLL_LOCKED; > > + if (!of_property_read_u32(node, "ti,min-div", &min_div) && > + min_div > dd->min_divider) > + dd->min_divider = min_div; > + > if (dpll_mode) > dd->modes = dpll_mode; > > @@ -585,8 +612,14 @@ static void __init of_ti_am3_no_gate_dpll_setup(struct device_node *node) > const struct dpll_data dd = { > .idlest_mask = 0x1, > .enable_mask = 0x7, > + .ssc_enable_mask = 0x1 << 12, > + .ssc_downspread_mask = 0x1 << 14, > .mult_mask = 0x7ff << 8, > .div1_mask = 0x7f, > + .ssc_deltam_int_mask = 0x3 << 18, > + .ssc_deltam_frac_mask = 0x3ffff, > + .ssc_modfreq_mant_mask = 0x7f, > + .ssc_modfreq_exp_mask = 0x7 << 8, > .max_multiplier = 2047, > .max_divider = 128, > .min_divider = 1, > @@ -645,8 +678,14 @@ static void __init of_ti_am3_dpll_setup(struct device_node *node) > const struct dpll_data dd = { > .idlest_mask = 0x1, > .enable_mask = 0x7, > + .ssc_enable_mask = 0x1 << 12, > + .ssc_downspread_mask = 0x1 << 14, > .mult_mask = 0x7ff << 8, > .div1_mask = 0x7f, > + .ssc_deltam_int_mask = 0x3 << 18, > + .ssc_deltam_frac_mask = 0x3ffff, > + .ssc_modfreq_mant_mask = 0x7f, > + .ssc_modfreq_exp_mask = 0x7 << 8, > .max_multiplier = 2047, > .max_divider = 128, > .min_divider = 1, > diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c > index 94d5b5fe9a2b..e32b3515f9e7 100644 > --- a/drivers/clk/ti/dpll3xxx.c > +++ b/drivers/clk/ti/dpll3xxx.c > @@ -291,6 +291,88 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n) > *sd_div = sd; > } > > +/** > + * omap3_noncore_dpll_ssc_program - set spread-spectrum clocking registers > + * @clk: struct clk * of DPLL to set > + * > + * Enable the DPLL spread spectrum clocking if frequency modulation and > + * frequency spreading have been set, otherwise disable it. > + */ > +static void omap3_noncore_dpll_ssc_program(struct clk_hw_omap *clk) > +{ > + struct dpll_data *dd = clk->dpll_data; > + unsigned long ref_rate; > + u32 v, ctrl, mod_freq_divider, exponent, mantissa; > + u32 deltam_step, deltam_ceil; > + > + ctrl = ti_clk_ll_ops->clk_readl(&dd->control_reg); > + > + if (dd->ssc_modfreq && dd->ssc_deltam) { > + ctrl |= dd->ssc_enable_mask; > + > + if (dd->ssc_downspread) > + ctrl |= dd->ssc_downspread_mask; > + else > + ctrl &= ~dd->ssc_downspread_mask; > + > + ref_rate = clk_hw_get_rate(dd->clk_ref); > + mod_freq_divider = > + (ref_rate / dd->last_rounded_n) / (4 * dd->ssc_modfreq); > + if (dd->ssc_modfreq > (ref_rate / 70)) > + pr_warn("clock: SSC modulation frequency of DPLL %s greater than %ld\n", > + __clk_get_name(clk->hw.clk), ref_rate / 70); > + > + exponent = 0; > + mantissa = mod_freq_divider; > + while ((mantissa > 127) && (exponent < 7)) { > + exponent++; > + mantissa /= 2; > + } > + if (mantissa > 127) > + mantissa = 127; > + > + v = ti_clk_ll_ops->clk_readl(&dd->ssc_modfreq_reg); > + v &= ~(dd->ssc_modfreq_mant_mask | dd->ssc_modfreq_exp_mask); > + v |= mantissa << __ffs(dd->ssc_modfreq_mant_mask); > + v |= exponent << __ffs(dd->ssc_modfreq_exp_mask); > + ti_clk_ll_ops->clk_writel(v, &dd->ssc_modfreq_reg); > + > + deltam_step = dd->last_rounded_m * dd->ssc_deltam; > + deltam_step /= 10; > + if (dd->ssc_downspread) > + deltam_step /= 2; > + > + deltam_step <<= __ffs(dd->ssc_deltam_int_mask); > + deltam_step /= 100; > + deltam_step /= mod_freq_divider; > + if (deltam_step > 0xFFFFF) > + deltam_step = 0xFFFFF; > + > + deltam_ceil = (deltam_step & dd->ssc_deltam_int_mask) >> > + __ffs(dd->ssc_deltam_int_mask); > + if (deltam_step & dd->ssc_deltam_frac_mask) > + deltam_ceil++; > + > + if ((dd->ssc_downspread && > + ((dd->last_rounded_m - (2 * deltam_ceil)) < 20 || > + dd->last_rounded_m > 2045)) || > + ((dd->last_rounded_m - deltam_ceil) < 20 || > + (dd->last_rounded_m + deltam_ceil) > 2045)) > + pr_warn("clock: SSC multiplier of DPLL %s is out of range\n", > + __clk_get_name(clk->hw.clk)); > + > + v = ti_clk_ll_ops->clk_readl(&dd->ssc_deltam_reg); > + v &= ~(dd->ssc_deltam_int_mask | dd->ssc_deltam_frac_mask); > + v |= deltam_step << __ffs(dd->ssc_deltam_int_mask | > + dd->ssc_deltam_frac_mask); > + ti_clk_ll_ops->clk_writel(v, &dd->ssc_deltam_reg); > + } else { > + ctrl &= ~dd->ssc_enable_mask; > + } > + > + ti_clk_ll_ops->clk_writel(ctrl, &dd->control_reg); > +} > + > /** > * omap3_noncore_dpll_program - set non-core DPLL M,N values directly > * @clk: struct clk * of DPLL to set > @@ -390,6 +472,9 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) > ti_clk_ll_ops->clk_writel(v, &dd->control_reg); > } > > + if (dd->ssc_enable_mask) > + omap3_noncore_dpll_ssc_program(clk); > + > /* We let the clock framework set the other output dividers later */ > > /* REVISIT: Set ramp-up delay? */ > diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h > index c62f6fa6763d..3486f20a3753 100644 > --- a/include/linux/clk/ti.h > +++ b/include/linux/clk/ti.h > @@ -63,6 +63,17 @@ struct clk_omap_reg { > * @auto_recal_bit: bitshift of the driftguard enable bit in @control_reg > * @recal_en_bit: bitshift of the PRM_IRQENABLE_* bit for recalibration IRQs > * @recal_st_bit: bitshift of the PRM_IRQSTATUS_* bit for recalibration IRQs > + * @ssc_deltam_reg: register containing the DPLL SSC frequency spreading > + * @ssc_modfreq_reg: register containing the DPLL SSC modulation frequency > + * @ssc_modfreq_mant_mask: mask of the mantissa component in @ssc_modfreq_reg > + * @ssc_modfreq_exp_mask: mask of the exponent component in @ssc_modfreq_reg > + * @ssc_enable_mask: mask of the DPLL SSC enable bit in @control_reg > + * @ssc_downspread_mask: mask of the DPLL SSC low frequency only bit in > + * @control_reg > + * @ssc_modfreq: the DPLL SSC frequency modulation in kHz > + * @ssc_deltam: the DPLL SSC frequency spreading in permille (10th of percent) > + * @ssc_downspread: require the only low frequency spread of the DPLL in SSC > + * mode > * @flags: DPLL type/features (see below) > * > * Possible values for @flags: > @@ -110,6 +121,17 @@ struct dpll_data { > u8 auto_recal_bit; > u8 recal_en_bit; > u8 recal_st_bit; > + struct clk_omap_reg ssc_deltam_reg; > + struct clk_omap_reg ssc_modfreq_reg; > + u32 ssc_deltam_int_mask; > + u32 ssc_deltam_frac_mask; > + u32 ssc_modfreq_mant_mask; > + u32 ssc_modfreq_exp_mask; > + u32 ssc_enable_mask; > + u32 ssc_downspread_mask; > + u32 ssc_modfreq; > + u32 ssc_deltam; > + bool ssc_downspread; > u8 flags; > }; > >
diff --git a/drivers/clk/ti/dpll.c b/drivers/clk/ti/dpll.c index d6f1ac5b53e1..e9f9aee936ae 100644 --- a/drivers/clk/ti/dpll.c +++ b/drivers/clk/ti/dpll.c @@ -290,7 +290,9 @@ static void __init of_ti_dpll_setup(struct device_node *node, struct clk_init_data *init = NULL; const char **parent_names = NULL; struct dpll_data *dd = NULL; + int ssc_clk_index; u8 dpll_mode = 0; + u32 min_div; dd = kmemdup(ddt, sizeof(*dd), GFP_KERNEL); clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL); @@ -345,6 +347,27 @@ static void __init of_ti_dpll_setup(struct device_node *node, if (dd->autoidle_mask) { if (ti_clk_get_reg_addr(node, 3, &dd->autoidle_reg)) goto cleanup; + + ssc_clk_index = 4; + } else { + ssc_clk_index = 3; + } + + if (dd->ssc_deltam_int_mask && dd->ssc_deltam_frac_mask && + dd->ssc_modfreq_mant_mask && dd->ssc_modfreq_exp_mask) { + if (ti_clk_get_reg_addr(node, ssc_clk_index++, + &dd->ssc_deltam_reg)) + goto cleanup; + + if (ti_clk_get_reg_addr(node, ssc_clk_index++, + &dd->ssc_modfreq_reg)) + goto cleanup; + + of_property_read_u32(node, "ti,ssc-modfreq-hz", + &dd->ssc_modfreq); + of_property_read_u32(node, "ti,ssc-deltam", &dd->ssc_deltam); + dd->ssc_downspread = + of_property_read_bool(node, "ti,ssc-downspread"); } if (of_property_read_bool(node, "ti,low-power-stop")) @@ -356,6 +379,10 @@ static void __init of_ti_dpll_setup(struct device_node *node, if (of_property_read_bool(node, "ti,lock")) dpll_mode |= 1 << DPLL_LOCKED; + if (!of_property_read_u32(node, "ti,min-div", &min_div) && + min_div > dd->min_divider) + dd->min_divider = min_div; + if (dpll_mode) dd->modes = dpll_mode; @@ -585,8 +612,14 @@ static void __init of_ti_am3_no_gate_dpll_setup(struct device_node *node) const struct dpll_data dd = { .idlest_mask = 0x1, .enable_mask = 0x7, + .ssc_enable_mask = 0x1 << 12, + .ssc_downspread_mask = 0x1 << 14, .mult_mask = 0x7ff << 8, .div1_mask = 0x7f, + .ssc_deltam_int_mask = 0x3 << 18, + .ssc_deltam_frac_mask = 0x3ffff, + .ssc_modfreq_mant_mask = 0x7f, + .ssc_modfreq_exp_mask = 0x7 << 8, .max_multiplier = 2047, .max_divider = 128, .min_divider = 1, @@ -645,8 +678,14 @@ static void __init of_ti_am3_dpll_setup(struct device_node *node) const struct dpll_data dd = { .idlest_mask = 0x1, .enable_mask = 0x7, + .ssc_enable_mask = 0x1 << 12, + .ssc_downspread_mask = 0x1 << 14, .mult_mask = 0x7ff << 8, .div1_mask = 0x7f, + .ssc_deltam_int_mask = 0x3 << 18, + .ssc_deltam_frac_mask = 0x3ffff, + .ssc_modfreq_mant_mask = 0x7f, + .ssc_modfreq_exp_mask = 0x7 << 8, .max_multiplier = 2047, .max_divider = 128, .min_divider = 1, diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c index 94d5b5fe9a2b..e32b3515f9e7 100644 --- a/drivers/clk/ti/dpll3xxx.c +++ b/drivers/clk/ti/dpll3xxx.c @@ -291,6 +291,88 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n) *sd_div = sd; } +/** + * omap3_noncore_dpll_ssc_program - set spread-spectrum clocking registers + * @clk: struct clk * of DPLL to set + * + * Enable the DPLL spread spectrum clocking if frequency modulation and + * frequency spreading have been set, otherwise disable it. + */ +static void omap3_noncore_dpll_ssc_program(struct clk_hw_omap *clk) +{ + struct dpll_data *dd = clk->dpll_data; + unsigned long ref_rate; + u32 v, ctrl, mod_freq_divider, exponent, mantissa; + u32 deltam_step, deltam_ceil; + + ctrl = ti_clk_ll_ops->clk_readl(&dd->control_reg); + + if (dd->ssc_modfreq && dd->ssc_deltam) { + ctrl |= dd->ssc_enable_mask; + + if (dd->ssc_downspread) + ctrl |= dd->ssc_downspread_mask; + else + ctrl &= ~dd->ssc_downspread_mask; + + ref_rate = clk_hw_get_rate(dd->clk_ref); + mod_freq_divider = + (ref_rate / dd->last_rounded_n) / (4 * dd->ssc_modfreq); + if (dd->ssc_modfreq > (ref_rate / 70)) + pr_warn("clock: SSC modulation frequency of DPLL %s greater than %ld\n", + __clk_get_name(clk->hw.clk), ref_rate / 70); + + exponent = 0; + mantissa = mod_freq_divider; + while ((mantissa > 127) && (exponent < 7)) { + exponent++; + mantissa /= 2; + } + if (mantissa > 127) + mantissa = 127; + + v = ti_clk_ll_ops->clk_readl(&dd->ssc_modfreq_reg); + v &= ~(dd->ssc_modfreq_mant_mask | dd->ssc_modfreq_exp_mask); + v |= mantissa << __ffs(dd->ssc_modfreq_mant_mask); + v |= exponent << __ffs(dd->ssc_modfreq_exp_mask); + ti_clk_ll_ops->clk_writel(v, &dd->ssc_modfreq_reg); + + deltam_step = dd->last_rounded_m * dd->ssc_deltam; + deltam_step /= 10; + if (dd->ssc_downspread) + deltam_step /= 2; + + deltam_step <<= __ffs(dd->ssc_deltam_int_mask); + deltam_step /= 100; + deltam_step /= mod_freq_divider; + if (deltam_step > 0xFFFFF) + deltam_step = 0xFFFFF; + + deltam_ceil = (deltam_step & dd->ssc_deltam_int_mask) >> + __ffs(dd->ssc_deltam_int_mask); + if (deltam_step & dd->ssc_deltam_frac_mask) + deltam_ceil++; + + if ((dd->ssc_downspread && + ((dd->last_rounded_m - (2 * deltam_ceil)) < 20 || + dd->last_rounded_m > 2045)) || + ((dd->last_rounded_m - deltam_ceil) < 20 || + (dd->last_rounded_m + deltam_ceil) > 2045)) + pr_warn("clock: SSC multiplier of DPLL %s is out of range\n", + __clk_get_name(clk->hw.clk)); + + v = ti_clk_ll_ops->clk_readl(&dd->ssc_deltam_reg); + v &= ~(dd->ssc_deltam_int_mask | dd->ssc_deltam_frac_mask); + v |= deltam_step << __ffs(dd->ssc_deltam_int_mask | + dd->ssc_deltam_frac_mask); + ti_clk_ll_ops->clk_writel(v, &dd->ssc_deltam_reg); + } else { + ctrl &= ~dd->ssc_enable_mask; + } + + ti_clk_ll_ops->clk_writel(ctrl, &dd->control_reg); +} + /** * omap3_noncore_dpll_program - set non-core DPLL M,N values directly * @clk: struct clk * of DPLL to set @@ -390,6 +472,9 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) ti_clk_ll_ops->clk_writel(v, &dd->control_reg); } + if (dd->ssc_enable_mask) + omap3_noncore_dpll_ssc_program(clk); + /* We let the clock framework set the other output dividers later */ /* REVISIT: Set ramp-up delay? */ diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h index c62f6fa6763d..3486f20a3753 100644 --- a/include/linux/clk/ti.h +++ b/include/linux/clk/ti.h @@ -63,6 +63,17 @@ struct clk_omap_reg { * @auto_recal_bit: bitshift of the driftguard enable bit in @control_reg * @recal_en_bit: bitshift of the PRM_IRQENABLE_* bit for recalibration IRQs * @recal_st_bit: bitshift of the PRM_IRQSTATUS_* bit for recalibration IRQs + * @ssc_deltam_reg: register containing the DPLL SSC frequency spreading + * @ssc_modfreq_reg: register containing the DPLL SSC modulation frequency + * @ssc_modfreq_mant_mask: mask of the mantissa component in @ssc_modfreq_reg + * @ssc_modfreq_exp_mask: mask of the exponent component in @ssc_modfreq_reg + * @ssc_enable_mask: mask of the DPLL SSC enable bit in @control_reg + * @ssc_downspread_mask: mask of the DPLL SSC low frequency only bit in + * @control_reg + * @ssc_modfreq: the DPLL SSC frequency modulation in kHz + * @ssc_deltam: the DPLL SSC frequency spreading in permille (10th of percent) + * @ssc_downspread: require the only low frequency spread of the DPLL in SSC + * mode * @flags: DPLL type/features (see below) * * Possible values for @flags: @@ -110,6 +121,17 @@ struct dpll_data { u8 auto_recal_bit; u8 recal_en_bit; u8 recal_st_bit; + struct clk_omap_reg ssc_deltam_reg; + struct clk_omap_reg ssc_modfreq_reg; + u32 ssc_deltam_int_mask; + u32 ssc_deltam_frac_mask; + u32 ssc_modfreq_mant_mask; + u32 ssc_modfreq_exp_mask; + u32 ssc_enable_mask; + u32 ssc_downspread_mask; + u32 ssc_modfreq; + u32 ssc_deltam; + bool ssc_downspread; u8 flags; };
The patch enables spread spectrum clocking (SSC) for MPU and LCD PLLs. As reported by the TI spruh73x/spruhl7x RM, SSC is only supported for the DISP/LCD and MPU PLLs on am33xx/am43xx. SSC is not supported for DDR, PER, and CORE PLLs. Calculating the required values and setting the registers accordingly was taken from the set_mpu_spreadspectrum routine contained in the arch/arm/mach-omap2/am33xx/clock_am33xx.c file of the u-boot project. In locked condition, DPLL output clock = CLKINP *[M/N]. In case of SSC enabled, the reference manual explains that there is a restriction of range of M values. Since the omap2_dpll_round_rate routine attempts to select the minimum possible N, the value of M obtained is not guaranteed to be within the range required. With the new "ti,min-div" parameter it is possible to increase N and consequently M to satisfy the constraint imposed by SSC. Signed-off-by: Dario Binacchi <dariobin@libero.it> --- Changes in v5: - Remove ssc_ack_mask field from dpll_data structure. It was not used. - Change ssc_downspread type from u8 to bool in dpll_data structure. Changes in v4: - Update commit message. Changes in v3: - Use "ti,ssc-modfreq-hz" binding instead of "ti,ssc-modfreq". Changes in v2: - Move the DT changes to the previous patch in the series. drivers/clk/ti/dpll.c | 39 ++++++++++++++++++ drivers/clk/ti/dpll3xxx.c | 85 +++++++++++++++++++++++++++++++++++++++ include/linux/clk/ti.h | 22 ++++++++++ 3 files changed, 146 insertions(+)