| Message ID | 1520930639-11642-1-git-send-email-mike.looijmans@topic.nl |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | clk: Add driver for the si544 clock generator chip | expand |
Hi Mike,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on v4.16-rc4]
[also build test WARNING on next-20180314]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Mike-Looijmans/clk-Add-driver-for-the-si544-clock-generator-chip/20180314-122736
smatch warnings:
drivers/clk/clk-si544.c:188 si544_calc_muldiv() warn: impossible condition '((frequency * tmp) >= 10800000000) => (0-u32max >= 10800000000)'
# https://github.com/0day-ci/linux/commit/aba3d3de8751c1457bcf0b75bcc901f289a18426
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout aba3d3de8751c1457bcf0b75bcc901f289a18426
vim +188 drivers/clk/clk-si544.c
aba3d3de Mike Looijmans 2018-03-13 168
aba3d3de Mike Looijmans 2018-03-13 169 /* Calculate divider settings for a given frequency */
aba3d3de Mike Looijmans 2018-03-13 170 static int si544_calc_muldiv(struct clk_si544_muldiv *settings,
aba3d3de Mike Looijmans 2018-03-13 171 unsigned long frequency)
aba3d3de Mike Looijmans 2018-03-13 172 {
aba3d3de Mike Looijmans 2018-03-13 173 u64 vco;
aba3d3de Mike Looijmans 2018-03-13 174 u32 ls_freq;
aba3d3de Mike Looijmans 2018-03-13 175 u32 tmp;
aba3d3de Mike Looijmans 2018-03-13 176 u8 res;
aba3d3de Mike Looijmans 2018-03-13 177
aba3d3de Mike Looijmans 2018-03-13 178 /* Determine the minimum value of LS_DIV and resulting target freq. */
aba3d3de Mike Looijmans 2018-03-13 179 ls_freq = frequency;
aba3d3de Mike Looijmans 2018-03-13 180 settings->ls_div_bits = 0;
aba3d3de Mike Looijmans 2018-03-13 181
aba3d3de Mike Looijmans 2018-03-13 182 if (frequency >= (FVCO_MIN / HS_DIV_MAX))
aba3d3de Mike Looijmans 2018-03-13 183 settings->ls_div_bits = 0;
aba3d3de Mike Looijmans 2018-03-13 184 else {
aba3d3de Mike Looijmans 2018-03-13 185 res = 1;
aba3d3de Mike Looijmans 2018-03-13 186 tmp = 2 * HS_DIV_MAX;
aba3d3de Mike Looijmans 2018-03-13 187 while (tmp <= (HS_DIV_MAX * 32)) {
aba3d3de Mike Looijmans 2018-03-13 @188 if ((frequency * tmp) >= FVCO_MIN)
aba3d3de Mike Looijmans 2018-03-13 189 break;
aba3d3de Mike Looijmans 2018-03-13 190 ++res;
aba3d3de Mike Looijmans 2018-03-13 191 tmp <<= 1;
aba3d3de Mike Looijmans 2018-03-13 192 }
aba3d3de Mike Looijmans 2018-03-13 193 settings->ls_div_bits = res;
aba3d3de Mike Looijmans 2018-03-13 194 ls_freq = frequency << res;
aba3d3de Mike Looijmans 2018-03-13 195 }
aba3d3de Mike Looijmans 2018-03-13 196
aba3d3de Mike Looijmans 2018-03-13 197 /* Determine minimum HS_DIV by rounding up */
aba3d3de Mike Looijmans 2018-03-13 198 vco = FVCO_MIN + ls_freq - 1;
aba3d3de Mike Looijmans 2018-03-13 199 do_div(vco, ls_freq);
aba3d3de Mike Looijmans 2018-03-13 200 settings->hs_div = vco;
aba3d3de Mike Looijmans 2018-03-13 201 /* round up to even number if needed */
aba3d3de Mike Looijmans 2018-03-13 202 if ((settings->hs_div > HS_DIV_MAX_ODD) && (settings->hs_div & 1))
aba3d3de Mike Looijmans 2018-03-13 203 ++settings->hs_div;
aba3d3de Mike Looijmans 2018-03-13 204 /* Calculate VCO frequency (in 10..12GHz range) */
aba3d3de Mike Looijmans 2018-03-13 205 vco = (u64)ls_freq * settings->hs_div;
aba3d3de Mike Looijmans 2018-03-13 206 /* Calculate the integer part of the feedback divider */
aba3d3de Mike Looijmans 2018-03-13 207 tmp = do_div(vco, FXO);
aba3d3de Mike Looijmans 2018-03-13 208 settings->fb_div_int = vco;
aba3d3de Mike Looijmans 2018-03-13 209 /* And the fractional bits using the remainder */
aba3d3de Mike Looijmans 2018-03-13 210 vco = (u64)tmp << 32;
aba3d3de Mike Looijmans 2018-03-13 211 do_div(vco, FXO);
aba3d3de Mike Looijmans 2018-03-13 212 settings->fb_div_frac = vco;
aba3d3de Mike Looijmans 2018-03-13 213
aba3d3de Mike Looijmans 2018-03-13 214 return 0;
aba3d3de Mike Looijmans 2018-03-13 215 }
aba3d3de Mike Looijmans 2018-03-13 216
---
0-DAY kernel test infrastructure Open Source Technology Center
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On 15-03-18 11:35, Dan Carpenter wrote: > Hi Mike, > > Thank you for the patch! Perhaps something to improve: > > [auto build test WARNING on v4.16-rc4] > [also build test WARNING on next-20180314] > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > url: https://github.com/0day-ci/linux/commits/Mike-Looijmans/clk-Add-driver-for-the-si544-clock-generator-chip/20180314-122736 > > smatch warnings: > drivers/clk/clk-si544.c:188 si544_calc_muldiv() warn: impossible condition '((frequency * tmp) >= 10800000000) => (0-u32max >= 10800000000)' Indeed, there's a u64 cast missing. I've also missed that the hs_div cannot be odd when ls_div is non-zero. I'll compose a v2 patch fixing these issues. > # https://github.com/0day-ci/linux/commit/aba3d3de8751c1457bcf0b75bcc901f289a18426 > git remote add linux-review https://github.com/0day-ci/linux > git remote update linux-review > git checkout aba3d3de8751c1457bcf0b75bcc901f289a18426 > vim +188 drivers/clk/clk-si544.c > > aba3d3de Mike Looijmans 2018-03-13 168 > aba3d3de Mike Looijmans 2018-03-13 169 /* Calculate divider settings for a given frequency */ > aba3d3de Mike Looijmans 2018-03-13 170 static int si544_calc_muldiv(struct clk_si544_muldiv *settings, > aba3d3de Mike Looijmans 2018-03-13 171 unsigned long frequency) > aba3d3de Mike Looijmans 2018-03-13 172 { > aba3d3de Mike Looijmans 2018-03-13 173 u64 vco; > aba3d3de Mike Looijmans 2018-03-13 174 u32 ls_freq; > aba3d3de Mike Looijmans 2018-03-13 175 u32 tmp; > aba3d3de Mike Looijmans 2018-03-13 176 u8 res; > aba3d3de Mike Looijmans 2018-03-13 177 > aba3d3de Mike Looijmans 2018-03-13 178 /* Determine the minimum value of LS_DIV and resulting target freq. */ > aba3d3de Mike Looijmans 2018-03-13 179 ls_freq = frequency; > aba3d3de Mike Looijmans 2018-03-13 180 settings->ls_div_bits = 0; > aba3d3de Mike Looijmans 2018-03-13 181 > aba3d3de Mike Looijmans 2018-03-13 182 if (frequency >= (FVCO_MIN / HS_DIV_MAX)) > aba3d3de Mike Looijmans 2018-03-13 183 settings->ls_div_bits = 0; > aba3d3de Mike Looijmans 2018-03-13 184 else { > aba3d3de Mike Looijmans 2018-03-13 185 res = 1; > aba3d3de Mike Looijmans 2018-03-13 186 tmp = 2 * HS_DIV_MAX; > aba3d3de Mike Looijmans 2018-03-13 187 while (tmp <= (HS_DIV_MAX * 32)) { > aba3d3de Mike Looijmans 2018-03-13 @188 if ((frequency * tmp) >= FVCO_MIN) > aba3d3de Mike Looijmans 2018-03-13 189 break; > aba3d3de Mike Looijmans 2018-03-13 190 ++res; > aba3d3de Mike Looijmans 2018-03-13 191 tmp <<= 1; > aba3d3de Mike Looijmans 2018-03-13 192 } > aba3d3de Mike Looijmans 2018-03-13 193 settings->ls_div_bits = res; > aba3d3de Mike Looijmans 2018-03-13 194 ls_freq = frequency << res; > aba3d3de Mike Looijmans 2018-03-13 195 } > aba3d3de Mike Looijmans 2018-03-13 196 > aba3d3de Mike Looijmans 2018-03-13 197 /* Determine minimum HS_DIV by rounding up */ > aba3d3de Mike Looijmans 2018-03-13 198 vco = FVCO_MIN + ls_freq - 1; > aba3d3de Mike Looijmans 2018-03-13 199 do_div(vco, ls_freq); > aba3d3de Mike Looijmans 2018-03-13 200 settings->hs_div = vco; > aba3d3de Mike Looijmans 2018-03-13 201 /* round up to even number if needed */ > aba3d3de Mike Looijmans 2018-03-13 202 if ((settings->hs_div > HS_DIV_MAX_ODD) && (settings->hs_div & 1)) > aba3d3de Mike Looijmans 2018-03-13 203 ++settings->hs_div; > aba3d3de Mike Looijmans 2018-03-13 204 /* Calculate VCO frequency (in 10..12GHz range) */ > aba3d3de Mike Looijmans 2018-03-13 205 vco = (u64)ls_freq * settings->hs_div; > aba3d3de Mike Looijmans 2018-03-13 206 /* Calculate the integer part of the feedback divider */ > aba3d3de Mike Looijmans 2018-03-13 207 tmp = do_div(vco, FXO); > aba3d3de Mike Looijmans 2018-03-13 208 settings->fb_div_int = vco; > aba3d3de Mike Looijmans 2018-03-13 209 /* And the fractional bits using the remainder */ > aba3d3de Mike Looijmans 2018-03-13 210 vco = (u64)tmp << 32; > aba3d3de Mike Looijmans 2018-03-13 211 do_div(vco, FXO); > aba3d3de Mike Looijmans 2018-03-13 212 settings->fb_div_frac = vco; > aba3d3de Mike Looijmans 2018-03-13 213 > aba3d3de Mike Looijmans 2018-03-13 214 return 0; > aba3d3de Mike Looijmans 2018-03-13 215 } > aba3d3de Mike Looijmans 2018-03-13 216 > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation > Kind regards, Mike Looijmans System Expert TOPIC Products Materiaalweg 4, NL-5681 RJ Best Postbus 440, NL-5680 AK Best Telefoon: +31 (0) 499 33 69 79 E-mail: mike.looijmans@topicproducts.com Website: www.topicproducts.com Please consider the environment before printing this e-mail -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoting Mike Looijmans (2018-03-13 01:43:59) > diff --git a/Documentation/devicetree/bindings/clock/silabs,si544.txt b/Documentation/devicetree/bindings/clock/silabs,si544.txt > new file mode 100644 > index 0000000..eec1787 > --- /dev/null > +++ b/Documentation/devicetree/bindings/clock/silabs,si544.txt > @@ -0,0 +1,25 @@ > +Binding for Silicon Labs 544 programmable I2C clock generator. > + > +Reference > +This binding uses the common clock binding[1]. Details about the device can be > +found in the datasheet[2]. > + > +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt > +[2] Si544 datasheet > + https://www.silabs.com/documents/public/data-sheets/si544-datasheet.pdf Can this reference stuff go to the bottom of this document? > + > +Required properties: > + - compatible: One of "silabs,si514a", "silabs,si514b" "silabs,si514c" according > + to the speed grade of the chip. > + - reg: I2C device address. > + - #clock-cells: From common clock bindings: Shall be 0. > + > +Optional properties: > + - clock-output-names: From common clock bindings. Recommended to be "si544". > + > +Example: > + si544: clock-generator@55 { I'm not sure clock-generator is in the list of node names, but we have some of these already so alright. > + reg = <0x55>; > + #clock-cells = <0>; > + compatible = "silabs,si544b"; > + }; > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig > index 98ce9fc..5c7dc8e 100644 > --- a/drivers/clk/Kconfig > +++ b/drivers/clk/Kconfig > @@ -91,6 +91,16 @@ config COMMON_CLK_SI514 > This driver supports the Silicon Labs 514 programmable clock > generator. > > +config COMMON_CLK_SI544 > + tristate "Clock driver for SiLabs 544 devices" > + depends on I2C > + depends on OF Does it depend on anything in OF to build? > + select REGMAP_I2C > + help > + ---help--- > + This driver supports the Silicon Labs 544 programmable clock > + generator. > + > config COMMON_CLK_SI570 > tristate "Clock driver for SiLabs 570 and compatible devices" > depends on I2C > diff --git a/drivers/clk/clk-si544.c b/drivers/clk/clk-si544.c > new file mode 100644 > index 0000000..1947e48 > --- /dev/null > +++ b/drivers/clk/clk-si544.c > @@ -0,0 +1,421 @@ > +/* > + * Driver for Silicon Labs Si544 Programmable Oscillator > + * > + * Copyright (C) 2018 Topic Embedded Products > + * > + * Author: Mike Looijmans <mike.looijmans@topic.nl> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. Can we have SPDX style license here? > + */ > + > +#include <linux/clk-provider.h> > +#include <linux/delay.h> > +#include <linux/module.h> > +#include <linux/i2c.h> > +#include <linux/regmap.h> > +#include <linux/slab.h> > + > +/* I2C registers (decimal as in datasheet) */ Heh. > +#define SI544_REG_CONTROL 7 > +#define SI544_REG_OE_STATE 17 > +#define SI544_REG_HS_DIV 23 > +#define SI544_REG_LS_HS_DIV 24 > +#define SI544_REG_FBDIV0 26 > +#define SI544_REG_FBDIV8 27 > +#define SI544_REG_FBDIV16 28 > +#define SI544_REG_FBDIV24 29 > +#define SI544_REG_FBDIV32 30 > +#define SI544_REG_FBDIV40 31 > +#define SI544_REG_FCAL_OVR 69 > +#define SI544_REG_ADPLL_DELTA_M0 231 > +#define SI544_REG_ADPLL_DELTA_M8 232 > +#define SI544_REG_ADPLL_DELTA_M16 233 > +#define SI544_REG_PAGE_SELECT 255 > + > +/* Register values */ > +#define SI544_CONTROL_RESET BIT(7) > +#define SI544_CONTROL_MS_ICAL2 BIT(3) > + > +#define SI544_OE_STATE_ODC_OE BIT(0) > + > +/* Max freq depends on speed grade */ > +#define SI544_MIN_FREQ 200000U > + > +/* Si544 Internal oscilator runs at 55.05 MHz */ > +#define FXO 55050000U > + > +/* VCO range is 10.8 .. 12.1 GHz, max depends on speed grade */ > +#define FVCO_MIN 10800000000ULL > + > +#define HS_DIV_MAX 2046 > +#define HS_DIV_MAX_ODD 33 > + > +enum si544_speed_grade { > + si544a, > + si544b, > + si544c, > +}; > + > +struct clk_si544 { > + struct clk_hw hw; > + struct regmap *regmap; > + struct i2c_client *i2c_client; > + enum si544_speed_grade speed_grade; > +}; > +#define to_clk_si544(_hw) container_of(_hw, struct clk_si544, hw) > + > +/* Multiplier/divider settings */ > +struct clk_si544_muldiv { > + u32 fb_div_frac; /* Integer part of feedback divider (32 bits) */ > + u16 fb_div_int; /* Fractional part of feedback divider (11 bits) */ > + u16 hs_div; /* 1st divider, 5..2046, must be even when >33 */ > + u8 ls_div_bits; /* 2nd divider, as 2^x, range 0..5 */ > +}; Can you use kernel-doc style instead of inline comments please. > + > +static bool is_valid_frequency(const struct clk_si544 *data, > + unsigned long frequency) > +{ > + unsigned long max_freq; > + > + if (frequency < SI544_MIN_FREQ) > + return false; > + > + switch (data->speed_grade) { > + case si544a: > + max_freq = 1500000000; > + break; > + case si544b: > + max_freq = 800000000; > + break; > + case si544c: > + max_freq = 350000000; > + break; > + default: > + return false; Drop this default case and let the compiler complain if we get a new enum to handle. > + } > + > + if (frequency > max_freq) > + return false; > + > + return true; Replace with 'return frequency <= max_freq'? > +} > + > +/* Calculate divider settings for a given frequency */ > +static int si544_calc_muldiv(struct clk_si544_muldiv *settings, > + unsigned long frequency) > +{ > + u64 vco; > + u32 ls_freq; > + u32 tmp; > + u8 res; > + > + /* Determine the minimum value of LS_DIV and resulting target freq. */ > + ls_freq = frequency; > + settings->ls_div_bits = 0; > + > + if (frequency >= (FVCO_MIN / HS_DIV_MAX)) Maybe FVCO_MIN/HS_DIV_MAX has a name that can be defined? MIN_DIV_FREQ? > + settings->ls_div_bits = 0; > + else { Style: Please add braces on the if arm too. > + res = 1; > + tmp = 2 * HS_DIV_MAX; > + while (tmp <= (HS_DIV_MAX * 32)) { > + if ((frequency * tmp) >= FVCO_MIN) > + break; > + ++res; > + tmp <<= 1; > + } > + settings->ls_div_bits = res; > + ls_freq = frequency << res; > + } > + > + /* Determine minimum HS_DIV by rounding up */ > + vco = FVCO_MIN + ls_freq - 1; > + do_div(vco, ls_freq); > + settings->hs_div = vco; > + /* round up to even number if needed */ > + if ((settings->hs_div > HS_DIV_MAX_ODD) && (settings->hs_div & 1)) Drop useless parenthesis please. > + ++settings->hs_div; > + /* Calculate VCO frequency (in 10..12GHz range) */ > + vco = (u64)ls_freq * settings->hs_div; > + /* Calculate the integer part of the feedback divider */ > + tmp = do_div(vco, FXO); > + settings->fb_div_int = vco; > + /* And the fractional bits using the remainder */ > + vco = (u64)tmp << 32; > + do_div(vco, FXO); > + settings->fb_div_frac = vco; This is all packed together. Please add a newline before each comment to make it easier to read. > + > + return 0; > +} > + > +/* Calculate resulting frequency given the register settings */ > +static unsigned long si544_calc_rate(struct clk_si544_muldiv *settings) > +{ > + u32 d = settings->hs_div * BIT(settings->ls_div_bits); > + u64 vco; > + > + /* Calculate VCO while preventing overflow */ > + vco = (u64)settings->fb_div_int * FXO; > + vco += (((u64)settings->fb_div_frac * FXO) + (FXO / 2)) >> 32; Yay for the smatch checking stuff on the list! Try to put things on more lines to keep stuff easier to follow. > + > + do_div(vco, d); > + > + return vco; > +} > + > +static unsigned long si544_recalc_rate(struct clk_hw *hw, > + unsigned long parent_rate) > +{ > + struct clk_si544 *data = to_clk_si544(hw); > + struct clk_si544_muldiv settings; > + int err; > + > + err = si544_get_muldiv(data, &settings); > + if (err) { > + dev_err(&data->i2c_client->dev, "unable to retrieve settings\n"); This error message could become quite spammy given that we typically call recalc_rate() many times. > + return 0; > + } > + > + return si544_calc_rate(&settings); > +} > + > +static long si544_round_rate(struct clk_hw *hw, unsigned long rate, > + unsigned long *parent_rate) > +{ > + struct clk_si544 *data = to_clk_si544(hw); > + struct clk_si544_muldiv settings; > + int err; > + > + if (!rate) > + return 0; Why? Do certain drivers call round_rate() with 0 and we want to ignore those cases and not return an error? > + > + if (!is_valid_frequency(data, rate)) > + return -EINVAL; > + > + err = si544_calc_muldiv(&settings, rate); > + if (err) > + return err; > + > + return si544_calc_rate(&settings); > +} > + > + [...] > + > +static int si544_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + struct clk_si544 *data; > + struct clk_init_data init; > + int err; > + > + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + init.ops = &si544_clk_ops; > + init.flags = 0; > + init.num_parents = 0; > + data->hw.init = &init; > + data->i2c_client = client; > + data->speed_grade = id->driver_data; > + > + if (of_property_read_string(client->dev.of_node, "clock-output-names", > + &init.name)) > + init.name = client->dev.of_node->name; > + > + data->regmap = devm_regmap_init_i2c(client, &si544_regmap_config); > + if (IS_ERR(data->regmap)) { > + dev_err(&client->dev, "failed to allocate register map\n"); Do we need another allocation failure message? > + return PTR_ERR(data->regmap); > + } > + > + i2c_set_clientdata(client, data); > + > + /* Select page 0, just to be sure, there appear to be no more */ > + err = regmap_write(data->regmap, SI544_REG_PAGE_SELECT, 0); > + if (err < 0) > + return err; > + > + err = devm_clk_hw_register(&client->dev, &data->hw); > + if (err) { > + dev_err(&client->dev, "clock registration failed\n"); > + return err; > + } > + err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, devm_of_clk_add_hw_provider()? > + &data->hw); > + if (err) { > + dev_err(&client->dev, "unable to add clk provider\n"); > + return err; > + } > + > + return 0; > +} > + > +static int si544_remove(struct i2c_client *client) > +{ > + of_clk_del_provider(client->dev.of_node); > + return 0; > +} Drop? -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/clock/silabs,si544.txt b/Documentation/devicetree/bindings/clock/silabs,si544.txt new file mode 100644 index 0000000..eec1787 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/silabs,si544.txt @@ -0,0 +1,25 @@ +Binding for Silicon Labs 544 programmable I2C clock generator. + +Reference +This binding uses the common clock binding[1]. Details about the device can be +found in the datasheet[2]. + +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt +[2] Si544 datasheet + https://www.silabs.com/documents/public/data-sheets/si544-datasheet.pdf + +Required properties: + - compatible: One of "silabs,si514a", "silabs,si514b" "silabs,si514c" according + to the speed grade of the chip. + - reg: I2C device address. + - #clock-cells: From common clock bindings: Shall be 0. + +Optional properties: + - clock-output-names: From common clock bindings. Recommended to be "si544". + +Example: + si544: clock-generator@55 { + reg = <0x55>; + #clock-cells = <0>; + compatible = "silabs,si544b"; + }; diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index 98ce9fc..5c7dc8e 100644 --- a/drivers/clk/Kconfig +++ b/drivers/clk/Kconfig @@ -91,6 +91,16 @@ config COMMON_CLK_SI514 This driver supports the Silicon Labs 514 programmable clock generator. +config COMMON_CLK_SI544 + tristate "Clock driver for SiLabs 544 devices" + depends on I2C + depends on OF + select REGMAP_I2C + help + ---help--- + This driver supports the Silicon Labs 544 programmable clock + generator. + config COMMON_CLK_SI570 tristate "Clock driver for SiLabs 570 and compatible devices" depends on I2C diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index 71ec41e..bde614a 100644 --- a/drivers/clk/Makefile +++ b/drivers/clk/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o obj-$(CONFIG_COMMON_CLK_SCPI) += clk-scpi.o obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o obj-$(CONFIG_COMMON_CLK_SI514) += clk-si514.o +obj-$(CONFIG_COMMON_CLK_SI544) += clk-si544.o obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o obj-$(CONFIG_ARCH_STM32) += clk-stm32f4.o obj-$(CONFIG_ARCH_STM32) += clk-stm32h7.o diff --git a/drivers/clk/clk-si544.c b/drivers/clk/clk-si544.c new file mode 100644 index 0000000..1947e48 --- /dev/null +++ b/drivers/clk/clk-si544.c @@ -0,0 +1,421 @@ +/* + * Driver for Silicon Labs Si544 Programmable Oscillator + * + * Copyright (C) 2018 Topic Embedded Products + * + * Author: Mike Looijmans <mike.looijmans@topic.nl> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/clk-provider.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/regmap.h> +#include <linux/slab.h> + +/* I2C registers (decimal as in datasheet) */ +#define SI544_REG_CONTROL 7 +#define SI544_REG_OE_STATE 17 +#define SI544_REG_HS_DIV 23 +#define SI544_REG_LS_HS_DIV 24 +#define SI544_REG_FBDIV0 26 +#define SI544_REG_FBDIV8 27 +#define SI544_REG_FBDIV16 28 +#define SI544_REG_FBDIV24 29 +#define SI544_REG_FBDIV32 30 +#define SI544_REG_FBDIV40 31 +#define SI544_REG_FCAL_OVR 69 +#define SI544_REG_ADPLL_DELTA_M0 231 +#define SI544_REG_ADPLL_DELTA_M8 232 +#define SI544_REG_ADPLL_DELTA_M16 233 +#define SI544_REG_PAGE_SELECT 255 + +/* Register values */ +#define SI544_CONTROL_RESET BIT(7) +#define SI544_CONTROL_MS_ICAL2 BIT(3) + +#define SI544_OE_STATE_ODC_OE BIT(0) + +/* Max freq depends on speed grade */ +#define SI544_MIN_FREQ 200000U + +/* Si544 Internal oscilator runs at 55.05 MHz */ +#define FXO 55050000U + +/* VCO range is 10.8 .. 12.1 GHz, max depends on speed grade */ +#define FVCO_MIN 10800000000ULL + +#define HS_DIV_MAX 2046 +#define HS_DIV_MAX_ODD 33 + +enum si544_speed_grade { + si544a, + si544b, + si544c, +}; + +struct clk_si544 { + struct clk_hw hw; + struct regmap *regmap; + struct i2c_client *i2c_client; + enum si544_speed_grade speed_grade; +}; +#define to_clk_si544(_hw) container_of(_hw, struct clk_si544, hw) + +/* Multiplier/divider settings */ +struct clk_si544_muldiv { + u32 fb_div_frac; /* Integer part of feedback divider (32 bits) */ + u16 fb_div_int; /* Fractional part of feedback divider (11 bits) */ + u16 hs_div; /* 1st divider, 5..2046, must be even when >33 */ + u8 ls_div_bits; /* 2nd divider, as 2^x, range 0..5 */ +}; + +/* Enables or disables the output driver */ +static int si544_enable_output(struct clk_si544 *data, bool enable) +{ + return regmap_update_bits(data->regmap, SI544_REG_OE_STATE, + SI544_OE_STATE_ODC_OE, enable ? SI544_OE_STATE_ODC_OE : 0); +} + +/* Retrieve clock multiplier and dividers from hardware */ +static int si544_get_muldiv(struct clk_si544 *data, + struct clk_si544_muldiv *settings) +{ + int err; + u8 reg[6]; + + err = regmap_bulk_read(data->regmap, SI544_REG_HS_DIV, reg, 2); + if (err) + return err; + + settings->ls_div_bits = (reg[1] >> 4) & 0x07; + settings->hs_div = (reg[1] & 0x07) << 8 | reg[0]; + + err = regmap_bulk_read(data->regmap, SI544_REG_FBDIV0, reg, 6); + if (err) + return err; + + settings->fb_div_int = reg[4] | (reg[5] & 0x07) << 8; + settings->fb_div_frac = reg[0] | reg[1] << 8 | reg[2] << 16 | + reg[3] << 24; + return 0; +} + +static int si544_set_muldiv(struct clk_si544 *data, + struct clk_si544_muldiv *settings) +{ + int err; + u8 reg[6]; + + reg[0] = settings->hs_div; + reg[1] = settings->hs_div >> 8 | settings->ls_div_bits << 4; + + err = regmap_bulk_write(data->regmap, SI544_REG_HS_DIV, reg, 2); + if (err < 0) + return err; + + reg[0] = settings->fb_div_frac; + reg[1] = settings->fb_div_frac >> 8; + reg[2] = settings->fb_div_frac >> 16; + reg[3] = settings->fb_div_frac >> 24; + reg[4] = settings->fb_div_int; + reg[5] = settings->fb_div_int >> 8; + + /* + * Writing to SI544_REG_FBDIV40 triggers the clock change, so that + * must be written last + */ + return regmap_bulk_write(data->regmap, SI544_REG_FBDIV0, reg, 6); +} + +static bool is_valid_frequency(const struct clk_si544 *data, + unsigned long frequency) +{ + unsigned long max_freq; + + if (frequency < SI544_MIN_FREQ) + return false; + + switch (data->speed_grade) { + case si544a: + max_freq = 1500000000; + break; + case si544b: + max_freq = 800000000; + break; + case si544c: + max_freq = 350000000; + break; + default: + return false; + } + + if (frequency > max_freq) + return false; + + return true; +} + +/* Calculate divider settings for a given frequency */ +static int si544_calc_muldiv(struct clk_si544_muldiv *settings, + unsigned long frequency) +{ + u64 vco; + u32 ls_freq; + u32 tmp; + u8 res; + + /* Determine the minimum value of LS_DIV and resulting target freq. */ + ls_freq = frequency; + settings->ls_div_bits = 0; + + if (frequency >= (FVCO_MIN / HS_DIV_MAX)) + settings->ls_div_bits = 0; + else { + res = 1; + tmp = 2 * HS_DIV_MAX; + while (tmp <= (HS_DIV_MAX * 32)) { + if ((frequency * tmp) >= FVCO_MIN) + break; + ++res; + tmp <<= 1; + } + settings->ls_div_bits = res; + ls_freq = frequency << res; + } + + /* Determine minimum HS_DIV by rounding up */ + vco = FVCO_MIN + ls_freq - 1; + do_div(vco, ls_freq); + settings->hs_div = vco; + /* round up to even number if needed */ + if ((settings->hs_div > HS_DIV_MAX_ODD) && (settings->hs_div & 1)) + ++settings->hs_div; + /* Calculate VCO frequency (in 10..12GHz range) */ + vco = (u64)ls_freq * settings->hs_div; + /* Calculate the integer part of the feedback divider */ + tmp = do_div(vco, FXO); + settings->fb_div_int = vco; + /* And the fractional bits using the remainder */ + vco = (u64)tmp << 32; + do_div(vco, FXO); + settings->fb_div_frac = vco; + + return 0; +} + +/* Calculate resulting frequency given the register settings */ +static unsigned long si544_calc_rate(struct clk_si544_muldiv *settings) +{ + u32 d = settings->hs_div * BIT(settings->ls_div_bits); + u64 vco; + + /* Calculate VCO while preventing overflow */ + vco = (u64)settings->fb_div_int * FXO; + vco += (((u64)settings->fb_div_frac * FXO) + (FXO / 2)) >> 32; + + do_div(vco, d); + + return vco; +} + +static unsigned long si544_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_si544 *data = to_clk_si544(hw); + struct clk_si544_muldiv settings; + int err; + + err = si544_get_muldiv(data, &settings); + if (err) { + dev_err(&data->i2c_client->dev, "unable to retrieve settings\n"); + return 0; + } + + return si544_calc_rate(&settings); +} + +static long si544_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct clk_si544 *data = to_clk_si544(hw); + struct clk_si544_muldiv settings; + int err; + + if (!rate) + return 0; + + if (!is_valid_frequency(data, rate)) + return -EINVAL; + + err = si544_calc_muldiv(&settings, rate); + if (err) + return err; + + return si544_calc_rate(&settings); +} + +/* + * Update output frequency for "big" frequency changes + */ +static int si544_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_si544 *data = to_clk_si544(hw); + struct clk_si544_muldiv settings; + int err; + + if (!is_valid_frequency(data, rate)) + return -EINVAL; + + err = si544_calc_muldiv(&settings, rate); + if (err) + return err; + + si544_enable_output(data, false); + + /* Allow FCAL for this frequency update */ + err = regmap_write(data->regmap, SI544_REG_FCAL_OVR, 0); + if (err < 0) + return err; + + + err = si544_set_muldiv(data, &settings); + if (err < 0) + return err; /* Undefined state now, best to leave disabled */ + + /* Trigger calibration */ + err = regmap_write(data->regmap, SI544_REG_CONTROL, + SI544_CONTROL_MS_ICAL2); + if (err < 0) + return err; + + /* Applying a new frequency can take up to 10ms */ + usleep_range(10000, 12000); + + si544_enable_output(data, true); + + return err; +} + +static const struct clk_ops si544_clk_ops = { + .recalc_rate = si544_recalc_rate, + .round_rate = si544_round_rate, + .set_rate = si544_set_rate, +}; + +static bool si544_regmap_is_volatile(struct device *dev, unsigned int reg) +{ + switch (reg) { + case SI544_REG_CONTROL: + case SI544_REG_FCAL_OVR: + return true; + default: + return false; + } +} + +static const struct regmap_config si544_regmap_config = { + .reg_bits = 8, + .val_bits = 8, + .cache_type = REGCACHE_RBTREE, + .max_register = SI544_REG_PAGE_SELECT, + .volatile_reg = si544_regmap_is_volatile, +}; + +static int si544_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct clk_si544 *data; + struct clk_init_data init; + int err; + + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + init.ops = &si544_clk_ops; + init.flags = 0; + init.num_parents = 0; + data->hw.init = &init; + data->i2c_client = client; + data->speed_grade = id->driver_data; + + if (of_property_read_string(client->dev.of_node, "clock-output-names", + &init.name)) + init.name = client->dev.of_node->name; + + data->regmap = devm_regmap_init_i2c(client, &si544_regmap_config); + if (IS_ERR(data->regmap)) { + dev_err(&client->dev, "failed to allocate register map\n"); + return PTR_ERR(data->regmap); + } + + i2c_set_clientdata(client, data); + + /* Select page 0, just to be sure, there appear to be no more */ + err = regmap_write(data->regmap, SI544_REG_PAGE_SELECT, 0); + if (err < 0) + return err; + + err = devm_clk_hw_register(&client->dev, &data->hw); + if (err) { + dev_err(&client->dev, "clock registration failed\n"); + return err; + } + err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, + &data->hw); + if (err) { + dev_err(&client->dev, "unable to add clk provider\n"); + return err; + } + + return 0; +} + +static int si544_remove(struct i2c_client *client) +{ + of_clk_del_provider(client->dev.of_node); + return 0; +} + +static const struct i2c_device_id si544_id[] = { + { "si544a", si544a }, + { "si544b", si544b }, + { "si544c", si544c }, + { } +}; +MODULE_DEVICE_TABLE(i2c, si544_id); + +static const struct of_device_id clk_si544_of_match[] = { + { .compatible = "silabs,si544a" }, + { .compatible = "silabs,si544b" }, + { .compatible = "silabs,si544c" }, + { }, +}; +MODULE_DEVICE_TABLE(of, clk_si544_of_match); + +static struct i2c_driver si544_driver = { + .driver = { + .name = "si544", + .of_match_table = clk_si544_of_match, + }, + .probe = si544_probe, + .remove = si544_remove, + .id_table = si544_id, +}; +module_i2c_driver(si544_driver); + +MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>"); +MODULE_DESCRIPTION("Si544 driver"); +MODULE_LICENSE("GPL");
This patch adds the driver and devicetree documentation for the Silicon Labs SI544 clock generator chip. This is an I2C controlled oscillator capable of generating clock signals ranging from 200kHz to 1500MHz. Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> --- .../devicetree/bindings/clock/silabs,si544.txt | 25 ++ drivers/clk/Kconfig | 10 + drivers/clk/Makefile | 1 + drivers/clk/clk-si544.c | 421 +++++++++++++++++++++ 4 files changed, 457 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/silabs,si544.txt create mode 100644 drivers/clk/clk-si544.c