The CREG block on lpc18xx contains configuration register for two low power clocks. Support enabling of these two clocks with a clk driver that access CREG trough the syscon regmap interface.
These clocks are needed to support peripherals like the internal RTC on lpc18xx. Signed-off-by: Joachim Eastwood <[email protected]> --- drivers/clk/nxp/Makefile | 1 + drivers/clk/nxp/clk-lpc18xx-creg.c | 173 +++++++++++++++++++++++++++++++++++++ 2 files changed, 174 insertions(+) create mode 100644 drivers/clk/nxp/clk-lpc18xx-creg.c diff --git a/drivers/clk/nxp/Makefile b/drivers/clk/nxp/Makefile index 7f608b0ad7b4..6f6b0f9aa320 100644 --- a/drivers/clk/nxp/Makefile +++ b/drivers/clk/nxp/Makefile @@ -1,2 +1,3 @@ obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-cgu.o obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-ccu.o +obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-creg.o diff --git a/drivers/clk/nxp/clk-lpc18xx-creg.c b/drivers/clk/nxp/clk-lpc18xx-creg.c new file mode 100644 index 000000000000..4bca11eca4a1 --- /dev/null +++ b/drivers/clk/nxp/clk-lpc18xx-creg.c @@ -0,0 +1,173 @@ +/* + * Clk driver for NXP LPC18xx/43xx Configuration Registers (CREG) + * + * Copyright (C) 2015 Joachim Eastwood <[email protected]> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/clk-provider.h> +#include <linux/delay.h> +#include <linux/kernel.h> +#include <linux/mfd/syscon.h> +#include <linux/of.h> +#include <linux/regmap.h> + +#define LPC18XX_CREG_CREG0 0x004 +#define LPC18XX_CREG_CREG0_EN1KHZ BIT(0) +#define LPC18XX_CREG_CREG0_EN32KHZ BIT(1) +#define LPC18XX_CREG_CREG0_RESET32KHZ BIT(2) +#define LPC18XX_CREG_CREG0_PD32KHZ BIT(3) + +#define to_clk_creg(_hw) container_of(_hw, struct clk_creg_data, hw) + +enum { + CREG_CLK_1KHZ, + CREG_CLK_32KHZ, + CREG_CLK_MAX, +}; + +struct clk_creg_data { + struct clk_hw hw; + const char *name; + struct regmap *reg; + unsigned int en_mask; + const struct clk_ops *ops; +}; + +#define CREG_CLK(_name, _emask, _ops) \ +{ \ + .name = _name, \ + .en_mask = LPC18XX_CREG_CREG0_##_emask, \ + .ops = &_ops, \ +} + +static int clk_creg_32k_prepare(struct clk_hw *hw) +{ + struct clk_creg_data *creg = to_clk_creg(hw); + int ret; + + ret = regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0, + LPC18XX_CREG_CREG0_PD32KHZ | + LPC18XX_CREG_CREG0_RESET32KHZ, 0); + + /* + * Powering up the 32k oscillator takes a long while + * and sadly there aren't any status bit to poll. + */ + msleep(2500); + + return ret; +} + +static void clk_creg_32k_unprepare(struct clk_hw *hw) +{ + struct clk_creg_data *creg = to_clk_creg(hw); + + regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0, + LPC18XX_CREG_CREG0_PD32KHZ, + LPC18XX_CREG_CREG0_PD32KHZ); +} + +static int clk_creg_32k_is_prepared(struct clk_hw *hw) +{ + struct clk_creg_data *creg = to_clk_creg(hw); + u32 reg; + + regmap_read(creg->reg, LPC18XX_CREG_CREG0, ®); + + return !(reg & LPC18XX_CREG_CREG0_PD32KHZ) && + !(reg & LPC18XX_CREG_CREG0_RESET32KHZ); +} + +static unsigned long clk_creg_1k_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + return parent_rate / 32; +} + +static int clk_creg_enable(struct clk_hw *hw) +{ + struct clk_creg_data *creg = to_clk_creg(hw); + + return regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0, + creg->en_mask, creg->en_mask); +} + +static void clk_creg_disable(struct clk_hw *hw) +{ + struct clk_creg_data *creg = to_clk_creg(hw); + + regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0, + creg->en_mask, 0); +} + +static const struct clk_ops clk_creg_32k = { + .enable = clk_creg_enable, + .disable = clk_creg_disable, + .prepare = clk_creg_32k_prepare, + .unprepare = clk_creg_32k_unprepare, + .is_prepared = clk_creg_32k_is_prepared, +}; + +static const struct clk_ops clk_creg_1k = { + .enable = clk_creg_enable, + .disable = clk_creg_disable, + .recalc_rate = clk_creg_1k_recalc_rate, +}; + +static struct clk_creg_data clk_creg_clocks[] = { + [CREG_CLK_1KHZ] = CREG_CLK("1khz_clk", EN1KHZ, clk_creg_1k), + [CREG_CLK_32KHZ] = CREG_CLK("32khz_clk", EN32KHZ, clk_creg_32k), +}; + +static struct clk *clk_register_creg_clk(struct clk_creg_data *creg_clk, + const char **parent_name, + struct regmap *syscon) +{ + struct clk_init_data init; + + init.ops = creg_clk->ops; + init.name = creg_clk->name; + init.parent_names = parent_name; + init.num_parents = 1; + + creg_clk->reg = syscon; + creg_clk->hw.init = &init; + + return clk_register(NULL, &creg_clk->hw); +} + +static struct clk *clk_creg[CREG_CLK_MAX]; +static struct clk_onecell_data clk_base_data = { + .clks = clk_creg, + .clk_num = CREG_CLK_MAX, +}; + +static void __init lpc18xx_creg_clk_init(struct device_node *np) +{ + const char *clk_32khz_parent; + struct regmap *syscon; + + syscon = syscon_node_to_regmap(np->parent); + if (IS_ERR(syscon)) { + pr_err("%s: syscon lookup failed\n", __func__); + return; + } + + clk_32khz_parent = of_clk_get_parent_name(np, 0); + + clk_creg[CREG_CLK_32KHZ] = + clk_register_creg_clk(&clk_creg_clocks[CREG_CLK_32KHZ], + &clk_32khz_parent, syscon); + + clk_creg[CREG_CLK_1KHZ] = + clk_register_creg_clk(&clk_creg_clocks[CREG_CLK_1KHZ], + &clk_creg_clocks[CREG_CLK_32KHZ].name, + syscon); + + of_clk_add_provider(np, of_clk_src_onecell_get, &clk_base_data); +} +CLK_OF_DECLARE(lpc18xx_creg_clk, "nxp,lpc1850-creg-clk", lpc18xx_creg_clk_init); -- 1.8.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
