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Message-ID: <f160590677d4eb03c31c7cb81fbca20d8916c460.camel@baylibre.com>
Subject: Re: [PATCH 3/3] clk: meson-g12a: add PCIE PLL clocks
From:   Jerome Brunet <jbrunet@baylibre.com>
To:     Neil Armstrong <narmstrong@baylibre.com>
Cc:     linux-clk@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Date:   Tue, 19 Mar 2019 10:55:56 +0100
In-Reply-To: <20190307141455.23879-4-narmstrong@baylibre.com>
References: <20190307141455.23879-1-narmstrong@baylibre.com>
         <20190307141455.23879-4-narmstrong@baylibre.com>
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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@baylibre.com>
> ---
>  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 ?

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>