Re: [PATCH 3/3] clk: meson-g12a: add PCIE PLL clocks

From: Neil Armstrong
Date: Tue Mar 19 2019 - 05:58:53 EST

On 19/03/2019 10:55, Jerome Brunet wrote:
> On Thu, 2019-03-07 at 15:14 +0100, Neil Armstrong wrote:
>> Add the PCIe reference clock feeding the USB3 + PCIE combo PHY.
>>
>> This PLL needs a very precise register sequence to permit to be locked,
>> thus using the specific clk-pll pcie ops.
>>
>> The PLL is then followed by :
>> - a fixed /2 divider
>> - a 5-bit 1-based divider
>> - a final /2 divider
>>
>> This reference clock is fixed to 100MHz, thus only a single PLL setup
>> is added.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>> ---
>> drivers/clk/meson/g12a.c | 118 +++++++++++++++++++++++++++++++++++++++
>> drivers/clk/meson/g12a.h | 5 +-
>> 2 files changed, 122 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
>> index 80a7172df2a6..d382c21a29e5 100644
>> --- a/drivers/clk/meson/g12a.c
>> +++ b/drivers/clk/meson/g12a.c
>> @@ -614,6 +614,118 @@ static struct clk_regmap g12a_hifi_pll = {
>> },
>> };
>>
>> +/*
>> + * The Meson G12A PCIE PLL is fined tuned to deliver a very precise
>> + * 100MHz reference clock for the PCIe Analog PHY, and thus requires
>> + * a strict register sequence to enable the PLL.
>> + */
>> +static const struct reg_sequence g12a_pcie_pll_init_regs[] = {
>> + { .reg = HHI_PCIE_PLL_CNTL0, .def = 0x20090496 },
>> + { .reg = HHI_PCIE_PLL_CNTL0, .def = 0x30090496 },
>> + { .reg = HHI_PCIE_PLL_CNTL1, .def = 0x00000000 },
>> + { .reg = HHI_PCIE_PLL_CNTL2, .def = 0x00001100 },
>> + { .reg = HHI_PCIE_PLL_CNTL3, .def = 0x10058e00 },
>> + { .reg = HHI_PCIE_PLL_CNTL4, .def = 0x000100c0 },
>> + { .reg = HHI_PCIE_PLL_CNTL5, .def = 0x68000048 },
>> + { .reg = HHI_PCIE_PLL_CNTL5, .def = 0x68000068, .delay_us = 20 },
>> + { .reg = HHI_PCIE_PLL_CNTL4, .def = 0x008100c0, .delay_us = 10 },
>> + { .reg = HHI_PCIE_PLL_CNTL0, .def = 0x34090496 },
>> + { .reg = HHI_PCIE_PLL_CNTL0, .def = 0x14090496, .delay_us = 10 },
>> + { .reg = HHI_PCIE_PLL_CNTL2, .def = 0x00001000 },
>> +};
>> +
>> +/* Keep a single entry table for recalc/round_rate() ops */
>> +static const struct pll_params_table g12a_pcie_pll_table[] = {
>> + PLL_PARAMS(150, 1),
>> + {0, 0},
>> +};
>> +
>> +static struct clk_regmap g12a_pcie_pll_dco = {
>> + .data = &(struct meson_clk_pll_data){
>> + .en = {
>> + .reg_off = HHI_PCIE_PLL_CNTL0,
>> + .shift = 28,
>> + .width = 1,
>> + },
>> + .m = {
>> + .reg_off = HHI_PCIE_PLL_CNTL0,
>> + .shift = 0,
>> + .width = 8,
>> + },
>> + .n = {
>> + .reg_off = HHI_PCIE_PLL_CNTL0,
>> + .shift = 10,
>> + .width = 5,
>> + },
>> + .frac = {
>> + .reg_off = HHI_PCIE_PLL_CNTL1,
>> + .shift = 0,
>> + .width = 12,
>> + },
>> + .l = {
>> + .reg_off = HHI_PCIE_PLL_CNTL0,
>> + .shift = 31,
>> + .width = 1,
>> + },
>> + .rst = {
>> + .reg_off = HHI_PCIE_PLL_CNTL0,
>> + .shift = 29,
>> + .width = 1,
>> + },
>> + .table = g12a_pcie_pll_table,
>> + .init_regs = g12a_pcie_pll_init_regs,
>> + .init_count = ARRAY_SIZE(g12a_pcie_pll_init_regs),
>> + },
>> + .hw.init = &(struct clk_init_data){
>> + .name = "pcie_pll_dco",
>> + .ops = &meson_clk_pcie_pll_ops,
>> + .parent_names = (const char *[]){ IN_PREFIX "xtal" },
>> + .num_parents = 1,
>> + },
>> +};
>> +
>> +static struct clk_fixed_factor g12a_pcie_pll_dco_div2 = {
>> + .mult = 1,
>> + .div = 2,
>> + .hw.init = &(struct clk_init_data){
>> + .name = "pcie_pll_dco_div2",
>> + .ops = &clk_fixed_factor_ops,
>> + .parent_names = (const char *[]){ "pcie_pll_dco" },
>> + .num_parents = 1,
>> + .flags = CLK_SET_RATE_PARENT,
>> + },
>> +};
>> +
>> +static struct clk_regmap g12a_pcie_pll_od = {
>> + .data = &(struct clk_regmap_div_data){
>> + .offset = HHI_PCIE_PLL_CNTL0,
>> + .shift = 16,
>> + .width = 5,
>> + .flags = CLK_DIVIDER_ROUND_CLOSEST |
>> + CLK_DIVIDER_ONE_BASED |
>> + CLK_DIVIDER_ALLOW_ZERO,
>
> That's unusual !
> Ods have always been power of two divider so far. I suppose you have noticed
> and checked this as well ?
>

Yes, I've checked and validated it. Without CLK_DIVIDER_ONE_BASED,
the divider is off by 1. And CLK_DIVIDER_ALLOW_ZERO since at reset,
0 is the default register value.

> That being said, the doc seems to imply that the global post divider will
> divide by 36, which seems difficult to reach with powers of two.
>
>> + },
>> + .hw.init = &(struct clk_init_data){
>> + .name = "pcie_pll_od",
>> + .ops = &clk_regmap_divider_ops,
>> + .parent_names = (const char *[]){ "pcie_pll_dco_div2" },
>> + .num_parents = 1,
>> + .flags = CLK_SET_RATE_PARENT,
>> + },
>> +};
>> +
>> +static struct clk_fixed_factor g12a_pcie_pll = {
>> + .mult = 1,
>> + .div = 2,
>> + .hw.init = &(struct clk_init_data){
>> + .name = "pcie_pll_pll",
>> + .ops = &clk_fixed_factor_ops,
>> + .parent_names = (const char *[]){ "pcie_pll_od" },
>> + .num_parents = 1,
>> + .flags = CLK_SET_RATE_PARENT,
>> + },
>> +};
>> +
>> static struct clk_regmap g12a_hdmi_pll_dco = {
>> .data = &(struct meson_clk_pll_data){
>> .en = {
>> @@ -2499,6 +2611,10 @@ static struct clk_hw_onecell_data g12a_hw_onecell_data = {
>> [CLKID_CPU_CLK_AXI] = &g12a_cpu_clk_axi.hw,
>> [CLKID_CPU_CLK_TRACE_DIV] = &g12a_cpu_clk_trace_div.hw,
>> [CLKID_CPU_CLK_TRACE] = &g12a_cpu_clk_trace.hw,
>> + [CLKID_PCIE_PLL_DCO] = &g12a_pcie_pll_dco.hw,
>> + [CLKID_PCIE_PLL_DCO_DIV2] = &g12a_pcie_pll_dco_div2.hw,
>> + [CLKID_PCIE_PLL_OD] = &g12a_pcie_pll_od.hw,
>> + [CLKID_PCIE_PLL] = &g12a_pcie_pll.hw,
>> [NR_CLKS] = NULL,
>> },
>> .num = NR_CLKS,
>> @@ -2685,6 +2801,8 @@ static struct clk_regmap *const g12a_clk_regmaps[] = {
>> &g12a_cpu_clk_axi,
>> &g12a_cpu_clk_trace_div,
>> &g12a_cpu_clk_trace,
>> + &g12a_pcie_pll_od,
>> + &g12a_pcie_pll_dco,
>> };
>>
>> static const struct meson_eeclkc_data g12a_clkc_data = {
>> diff --git a/drivers/clk/meson/g12a.h b/drivers/clk/meson/g12a.h
>> index 70aa469ca1cf..1393a09730a6 100644
>> --- a/drivers/clk/meson/g12a.h
>> +++ b/drivers/clk/meson/g12a.h
>> @@ -186,8 +186,11 @@
>> #define CLKID_CPU_CLK_AXI 195
>> #define CLKID_CPU_CLK_TRACE_DIV 196
>> #define CLKID_CPU_CLK_TRACE 197
>> +#define CLKID_PCIE_PLL_DCO 198
>> +#define CLKID_PCIE_PLL_DCO_DIV2 199
>> +#define CLKID_PCIE_PLL_OD 200
>>
>> -#define NR_CLKS 198
>> +#define NR_CLKS 202
>>
>> /* include the CLKIDs that have been made part of the DT binding */
>> #include <dt-bindings/clock/g12a-clkc.h>
>
>