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SubjectRE: [PATCH 2/4] clk: ast2600: Add functionality to the APLL clock
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Hello Eddie,
For FSI design is request for two clock source.
one for FSI core, one for FSI bus clock.
In AST2600 FSI core clk is apll, FSI bus clock need apll/4.
So, you should fix for fsi clock input. Not set from fsi-master-driver.
And fsi-master driver div from clock source apll/4. Should not set for apll from fsi-master driver.

> -----Original Message-----
> From: Joel Stanley <joel@jms.id.au>
> Sent: Friday, September 11, 2020 9:30 AM
> To: Eddie James <eajames@linux.ibm.com>; Ryan Chen
> <ryan_chen@aspeedtech.com>; Billy Tsai <billy_tsai@aspeedtech.com>
> Cc: linux-clk@vger.kernel.org; Linux Kernel Mailing List
> <linux-kernel@vger.kernel.org>; devicetree <devicetree@vger.kernel.org>;
> linux-aspeed <linux-aspeed@lists.ozlabs.org>; linux-fsi@lists.ozlabs.org;
> Andrew Jeffery <andrew@aj.id.au>; Rob Herring <robh+dt@kernel.org>;
> Stephen Boyd <sboyd@kernel.org>; Michael Turquette
> <mturquette@baylibre.com>; Alistair Popple <alistair@popple.id.au>; Jeremy
> Kerr <jk@ozlabs.org>
> Subject: Re: [PATCH 2/4] clk: ast2600: Add functionality to the APLL clock
>
> Ryan,
>
> This change adds support for setting the A-PLL in the 2600 so we can control
> the FSI frequency. Can your team please review it? If it is okay please reply
> with your Reviewed-by.
>
>
> On Thu, 10 Sep 2020 at 15:18, Eddie James <eajames@linux.ibm.com> wrote:
> >
> > Register a clock with it's own operations to describe the APLL on the
> > AST2600. The clock is controlled by an SCU register containing a
> > multiplier and divider of the 25MHz input clock.
> > The functionality to change the APLL is necessary to finely control
> > the FSI bus frequency.
> >
> > Signed-off-by: Eddie James <eajames@linux.ibm.com>
> > ---
> > drivers/clk/clk-ast2600.c | 177
> > +++++++++++++++++++++++++++++++++++---
> > 1 file changed, 165 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
> > index 177368cac6dd..a147dffbaccc 100644
> > --- a/drivers/clk/clk-ast2600.c
> > +++ b/drivers/clk/clk-ast2600.c
> > @@ -4,6 +4,7 @@
> >
> > #define pr_fmt(fmt) "clk-ast2600: " fmt
> >
> > +#include <linux/kernel.h>
> > #include <linux/mfd/syscon.h>
> > #include <linux/of_address.h>
> > #include <linux/of_device.h>
> > @@ -15,7 +16,7 @@
> >
> > #include "clk-aspeed.h"
> >
> > -#define ASPEED_G6_NUM_CLKS 71
> > +#define ASPEED_G6_NUM_CLKS 72
> >
> > #define ASPEED_G6_SILICON_REV 0x004
> >
> > @@ -31,6 +32,7 @@
> > #define ASPEED_G6_CLK_SELECTION1 0x300
> > #define ASPEED_G6_CLK_SELECTION2 0x304
> > #define ASPEED_G6_CLK_SELECTION4 0x310
> > +#define ASPEED_G6_CLK_SELECTION5 0x314
> >
> > #define ASPEED_HPLL_PARAM 0x200
> > #define ASPEED_APLL_PARAM 0x210
> > @@ -116,7 +118,7 @@ static const struct aspeed_gate_data
> aspeed_g6_gates[] = {
> > [ASPEED_CLK_GATE_UART11CLK] = { 59, -1,
> "uart11clk-gate", "uartx", 0 }, /* UART11 */
> > [ASPEED_CLK_GATE_UART12CLK] = { 60, -1,
> "uart12clk-gate", "uartx", 0 }, /* UART12 */
> > [ASPEED_CLK_GATE_UART13CLK] = { 61, -1,
> "uart13clk-gate", "uartx", 0 }, /* UART13 */
> > - [ASPEED_CLK_GATE_FSICLK] = { 62, 59, "fsiclk-gate",
> NULL, 0 }, /* FSI */
> > + [ASPEED_CLK_GATE_FSICLK] = { 62, 59, "fsiclk-gate",
> "aplln", CLK_SET_RATE_PARENT }, /* FSI */
>
> Why do we call this apll*n* ?
>
> I believe the apll is also the parent of the sdclk.
>
> Designs that use FSI do not use the sdclk, but it should be added to the table
> for completeness.
>
> > };
> >
> > static const struct clk_div_table ast2600_eclk_div_table[] = { @@
> > -187,24 +189,166 @@ static struct clk_hw *ast2600_calc_pll(const char
> *name, u32 val)
> > mult, div);
> > };
> >
> > -static struct clk_hw *ast2600_calc_apll(const char *name, u32 val)
> > +/*
> > + * APLL Frequency: F = 25MHz * (2 - od) * [(m + 2) / (n + 1)] */
> > +static void ast2600_apll_get_params(unsigned int *div, unsigned int
> > +*mul)
> > {
> > - unsigned int mult, div;
> > + u32 val = readl(scu_g6_base + ASPEED_APLL_PARAM);
> >
> > if (val & BIT(20)) {
> > /* Pass through mode */
> > - mult = div = 1;
> > + *mul = *div = 1;
> > } else {
> > - /* F = 25Mhz * (2-od) * [(m + 2) / (n + 1)] */
> > u32 m = (val >> 5) & 0x3f;
> > u32 od = (val >> 4) & 0x1;
> > u32 n = val & 0xf;
> >
> > - mult = (2 - od) * (m + 2);
> > - div = n + 1;
> > + *mul = (2 - od) * (m + 2);
> > + *div = n + 1;
> > }
> > - return clk_hw_register_fixed_factor(NULL, name, "clkin", 0,
> > - mult, div);
> > +}
> > +
> > +static long ast2600_apll_best(unsigned long ul_rate, unsigned long
> ul_prate,
> > + unsigned int *out_div, unsigned int
> *out_mul,
> > + unsigned int *output_divider) {
>
> I look to our clk maintainers for review of this bit. Eddie has done a good job,
> but if there's a better way to do this then please let us know.
>
> In practice we will run the APLL at one of two rates, so doing a search during
> every boot seems unnecessary to me.
>
> > +#define min_mult 2ULL
> > +#define max_mult 65ULL
> > +#define min_div 1ULL
> > +#define max_div 16ULL
> > + int i;
> > + unsigned int bod = 0;
> > + unsigned long long rem = 1ULL;
> > + unsigned long long brem = ~(0ULL);
> > + unsigned long long bdiv = 1ULL;
> > + unsigned long long tdiv;
> > + unsigned long long bmul = 16ULL;
> > + unsigned long long tmul;
> > + long brate = -ERANGE;
> > + unsigned long long trate;
> > + unsigned long long rate = ul_rate;
> > + unsigned long long prate = ul_prate;
> > +
> > + for (i = 0; i < 2; ++i, prate *= 2ULL) {
> > + for (tdiv = min_div; tdiv <= max_div; ++tdiv) {
> > + tmul = DIV_ROUND_CLOSEST_ULL(rate * tdiv,
> prate);
> > + if (tmul < min_mult || tmul > max_mult)
> > + continue;
> > +
> > + trate = DIV_ROUND_CLOSEST_ULL(prate * tmul,
> tdiv);
> > + if (trate > rate)
> > + rem = trate - rate;
> > + else
> > + rem = rate - trate;
> > +
> > + if (rem < brem) {
> > + bod = !i;
> > + brem = rem;
> > + bdiv = tdiv;
> > + bmul = tmul;
> > + brate = (long)trate;
> > + }
> > +
> > + if (!rem)
> > + break;
> > + }
> > +
> > + if (!rem)
> > + break;
> > + }
> > +
> > + if (out_div)
> > + *out_div = (unsigned int)bdiv;
> > +
> > + if (out_mul)
> > + *out_mul = (unsigned int)bmul;
> > +
> > + if (output_divider)
> > + *output_divider = bod;
> > +
> > + return brate;
> > +#undef min_mult
> > +#undef max_mult
> > +#undef min_div
> > +#undef max_div
> > +}
> > +
> > +static unsigned long ast2600_apll_recalc_rate(struct clk_hw *hw,
> > + unsigned long
> > +parent_rate) {
> > + unsigned int div;
> > + unsigned int mul;
> > + unsigned long long rate;
> > + unsigned long long prate = (unsigned long long)parent_rate;
> > +
> > + ast2600_apll_get_params(&div, &mul);
> > +
> > + rate = DIV_ROUND_CLOSEST_ULL(prate * (unsigned long long)mul,
> div);
> > + return (unsigned long)rate;
> > +}
> > +
> > +static long ast2600_apll_round_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long *parent_rate) {
> > + return ast2600_apll_best(rate, *parent_rate, NULL, NULL,
> > +NULL); }
> > +
> > +static int ast2600_apll_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate) {
> > + u32 val;
> > + unsigned int od;
> > + unsigned int div;
> > + unsigned int mul;
> > + long brate = ast2600_apll_best(rate, parent_rate, &div, &mul,
> > +&od);
> > +
> > + if (brate < 0)
> > + return brate;
> > +
> > + val = readl(scu_g6_base + ASPEED_APLL_PARAM);
> > + val &= ~0x7ff;
> > + val |= (div - 1) & 0xf;
> > + val |= ((mul - 2) & 0x3f) << 5;
> > + if (od)
> > + val |= 0x10;
> > + writel(val, scu_g6_base + ASPEED_APLL_PARAM);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct clk_ops ast2600_apll_ops = {
> > + .recalc_rate = ast2600_apll_recalc_rate,
> > + .round_rate = ast2600_apll_round_rate,
> > + .set_rate = ast2600_apll_set_rate, };
> > +
> > +static struct clk_hw *ast2600_create_apll(void) {
> > + int rc;
> > + const char *parent = "clkin";
> > + struct clk_init_data init = {
> > + .name = "apll",
> > + .ops = &ast2600_apll_ops,
> > + .parent_names = &parent,
> > + .parent_data = NULL,
> > + .parent_hws = NULL,
> > + .num_parents = 1,
> > + .flags = 0,
> > + };
> > + struct clk_hw *clk = kzalloc(sizeof(*clk), GFP_KERNEL);
> > +
> > + if (!clk)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + clk->init = &init;
> > + rc = of_clk_hw_register(NULL, clk);
> > + if (rc) {
> > + kfree(clk);
> > + clk = ERR_PTR(rc);
> > + }
> > +
> > + return clk;
> > };
> >
> > static u32 get_bit(u8 idx)
> > @@ -630,6 +774,16 @@ static int aspeed_g6_clk_probe(struct
> platform_device *pdev)
> > return PTR_ERR(hw);
> > aspeed_g6_clk_data->hws[ASPEED_CLK_ECLK] = hw;
> >
> > + hw = clk_hw_register_divider_table(dev, "aplln", "apll",
> > + CLK_SET_RATE_PARENT,
> > + scu_g6_base +
> ASPEED_G6_CLK_SELECTION5,
> > + 28, 3,
> CLK_DIVIDER_READ_ONLY,
> > + ast2600_eclk_div_table,
> > + &aspeed_g6_clk_lock);
> > + if (IS_ERR(hw))
> > + return PTR_ERR(hw);
> > + aspeed_g6_clk_data->hws[ASPEED_CLK_APLLN] = hw;
> > +
> > for (i = 0; i < ARRAY_SIZE(aspeed_g6_gates); i++) {
> > const struct aspeed_gate_data *gd =
> &aspeed_g6_gates[i];
> > u32 gate_flags;
> > @@ -710,8 +864,7 @@ static void __init aspeed_g6_cc(struct regmap
> *map)
> > regmap_read(map, ASPEED_EPLL_PARAM, &val);
> > aspeed_g6_clk_data->hws[ASPEED_CLK_EPLL] =
> > ast2600_calc_pll("epll", val);
> >
> > - regmap_read(map, ASPEED_APLL_PARAM, &val);
> > - aspeed_g6_clk_data->hws[ASPEED_CLK_APLL] =
> ast2600_calc_apll("apll", val);
> > + aspeed_g6_clk_data->hws[ASPEED_CLK_APLL] =
> > + ast2600_create_apll();
> >
> > /* Strap bits 12:11 define the AXI/AHB clock frequency ratio (aka
> HCLK)*/
> > regmap_read(map, ASPEED_G6_STRAP1, &val);
> > --
> > 2.26.2
> >
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