root/drivers/clk/nxp/clk-lpc18xx-ccu.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Clk driver for NXP LPC18xx/LPC43xx Clock Control Unit (CCU)
 *
 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/string.h>

#include <dt-bindings/clock/lpc18xx-ccu.h>

/* Bit defines for CCU branch configuration register */
#define LPC18XX_CCU_RUN         BIT(0)
#define LPC18XX_CCU_AUTO        BIT(1)
#define LPC18XX_CCU_DIV         BIT(5)
#define LPC18XX_CCU_DIVSTAT     BIT(27)

/* CCU branch feature bits */
#define CCU_BRANCH_IS_BUS       BIT(0)
#define CCU_BRANCH_HAVE_DIV2    BIT(1)

struct lpc18xx_branch_clk_data {
        const char **name;
        int num;
};

struct lpc18xx_clk_branch {
        const char *base_name;
        const char *name;
        u16 offset;
        u16 flags;
        struct clk *clk;
        struct clk_gate gate;
};

static struct lpc18xx_clk_branch clk_branches[] = {
        {"base_apb3_clk", "apb3_bus",           CLK_APB3_BUS,           CCU_BRANCH_IS_BUS},
        {"base_apb3_clk", "apb3_i2c1",          CLK_APB3_I2C1,          0},
        {"base_apb3_clk", "apb3_dac",           CLK_APB3_DAC,           0},
        {"base_apb3_clk", "apb3_adc0",          CLK_APB3_ADC0,          0},
        {"base_apb3_clk", "apb3_adc1",          CLK_APB3_ADC1,          0},
        {"base_apb3_clk", "apb3_can0",          CLK_APB3_CAN0,          0},

        {"base_apb1_clk", "apb1_bus",           CLK_APB1_BUS,           CCU_BRANCH_IS_BUS},
        {"base_apb1_clk", "apb1_mc_pwm",        CLK_APB1_MOTOCON_PWM,   0},
        {"base_apb1_clk", "apb1_i2c0",          CLK_APB1_I2C0,          0},
        {"base_apb1_clk", "apb1_i2s",           CLK_APB1_I2S,           0},
        {"base_apb1_clk", "apb1_can1",          CLK_APB1_CAN1,          0},

        {"base_spifi_clk", "spifi",             CLK_SPIFI,              0},

        {"base_cpu_clk", "cpu_bus",             CLK_CPU_BUS,            CCU_BRANCH_IS_BUS},
        {"base_cpu_clk", "cpu_spifi",           CLK_CPU_SPIFI,          0},
        {"base_cpu_clk", "cpu_gpio",            CLK_CPU_GPIO,           0},
        {"base_cpu_clk", "cpu_lcd",             CLK_CPU_LCD,            0},
        {"base_cpu_clk", "cpu_ethernet",        CLK_CPU_ETHERNET,       0},
        {"base_cpu_clk", "cpu_usb0",            CLK_CPU_USB0,           0},
        {"base_cpu_clk", "cpu_emc",             CLK_CPU_EMC,            0},
        {"base_cpu_clk", "cpu_sdio",            CLK_CPU_SDIO,           0},
        {"base_cpu_clk", "cpu_dma",             CLK_CPU_DMA,            0},
        {"base_cpu_clk", "cpu_core",            CLK_CPU_CORE,           0},
        {"base_cpu_clk", "cpu_sct",             CLK_CPU_SCT,            0},
        {"base_cpu_clk", "cpu_usb1",            CLK_CPU_USB1,           0},
        {"base_cpu_clk", "cpu_emcdiv",          CLK_CPU_EMCDIV,         CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_flasha",          CLK_CPU_FLASHA,         CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_flashb",          CLK_CPU_FLASHB,         CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_m0app",           CLK_CPU_M0APP,          CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_adchs",           CLK_CPU_ADCHS,          CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_eeprom",          CLK_CPU_EEPROM,         CCU_BRANCH_HAVE_DIV2},
        {"base_cpu_clk", "cpu_wwdt",            CLK_CPU_WWDT,           0},
        {"base_cpu_clk", "cpu_uart0",           CLK_CPU_UART0,          0},
        {"base_cpu_clk", "cpu_uart1",           CLK_CPU_UART1,          0},
        {"base_cpu_clk", "cpu_ssp0",            CLK_CPU_SSP0,           0},
        {"base_cpu_clk", "cpu_timer0",          CLK_CPU_TIMER0,         0},
        {"base_cpu_clk", "cpu_timer1",          CLK_CPU_TIMER1,         0},
        {"base_cpu_clk", "cpu_scu",             CLK_CPU_SCU,            0},
        {"base_cpu_clk", "cpu_creg",            CLK_CPU_CREG,           0},
        {"base_cpu_clk", "cpu_ritimer",         CLK_CPU_RITIMER,        0},
        {"base_cpu_clk", "cpu_uart2",           CLK_CPU_UART2,          0},
        {"base_cpu_clk", "cpu_uart3",           CLK_CPU_UART3,          0},
        {"base_cpu_clk", "cpu_timer2",          CLK_CPU_TIMER2,         0},
        {"base_cpu_clk", "cpu_timer3",          CLK_CPU_TIMER3,         0},
        {"base_cpu_clk", "cpu_ssp1",            CLK_CPU_SSP1,           0},
        {"base_cpu_clk", "cpu_qei",             CLK_CPU_QEI,            0},

        {"base_periph_clk", "periph_bus",       CLK_PERIPH_BUS,         CCU_BRANCH_IS_BUS},
        {"base_periph_clk", "periph_core",      CLK_PERIPH_CORE,        0},
        {"base_periph_clk", "periph_sgpio",     CLK_PERIPH_SGPIO,       0},

        {"base_usb0_clk",  "usb0",              CLK_USB0,               0},
        {"base_usb1_clk",  "usb1",              CLK_USB1,               0},
        {"base_spi_clk",   "spi",               CLK_SPI,                0},
        {"base_adchs_clk", "adchs",             CLK_ADCHS,              0},

        {"base_audio_clk", "audio",             CLK_AUDIO,              0},
        {"base_uart3_clk", "apb2_uart3",        CLK_APB2_UART3,         0},
        {"base_uart2_clk", "apb2_uart2",        CLK_APB2_UART2,         0},
        {"base_uart1_clk", "apb0_uart1",        CLK_APB0_UART1,         0},
        {"base_uart0_clk", "apb0_uart0",        CLK_APB0_UART0,         0},
        {"base_ssp1_clk",  "apb2_ssp1",         CLK_APB2_SSP1,          0},
        {"base_ssp0_clk",  "apb0_ssp0",         CLK_APB0_SSP0,          0},
        {"base_sdio_clk",  "sdio",              CLK_SDIO,               0},
};

static struct clk *lpc18xx_ccu_branch_clk_get(struct of_phandle_args *clkspec,
                                              void *data)
{
        struct lpc18xx_branch_clk_data *clk_data = data;
        unsigned int offset = clkspec->args[0];
        int i, j;

        for (i = 0; i < ARRAY_SIZE(clk_branches); i++) {
                if (clk_branches[i].offset != offset)
                        continue;

                for (j = 0; j < clk_data->num; j++) {
                        if (!strcmp(clk_branches[i].base_name, clk_data->name[j]))
                                return clk_branches[i].clk;
                }
        }

        pr_err("%s: invalid clock offset %d\n", __func__, offset);

        return ERR_PTR(-EINVAL);
}

static int lpc18xx_ccu_gate_endisable(struct clk_hw *hw, bool enable)
{
        struct clk_gate *gate = to_clk_gate(hw);
        u32 val;

        /*
         * Divider field is write only, so divider stat field must
         * be read so divider field can be set accordingly.
         */
        val = readl(gate->reg);
        if (val & LPC18XX_CCU_DIVSTAT)
                val |= LPC18XX_CCU_DIV;

        if (enable) {
                val |= LPC18XX_CCU_RUN;
        } else {
                /*
                 * To safely disable a branch clock a sequence of two separate
                 * writes must be used. First write should set the AUTO bit
                 * and the next write should clear the RUN bit.
                 */
                val |= LPC18XX_CCU_AUTO;
                writel(val, gate->reg);

                val &= ~LPC18XX_CCU_RUN;
        }

        writel(val, gate->reg);

        return 0;
}

static int lpc18xx_ccu_gate_enable(struct clk_hw *hw)
{
        return lpc18xx_ccu_gate_endisable(hw, true);
}

static void lpc18xx_ccu_gate_disable(struct clk_hw *hw)
{
        lpc18xx_ccu_gate_endisable(hw, false);
}

static int lpc18xx_ccu_gate_is_enabled(struct clk_hw *hw)
{
        const struct clk_hw *parent;

        /*
         * The branch clock registers are only accessible
         * if the base (parent) clock is enabled. Register
         * access with a disabled base clock will hang the
         * system.
         */
        parent = clk_hw_get_parent(hw);
        if (!parent)
                return 0;

        if (!clk_hw_is_enabled(parent))
                return 0;

        return clk_gate_ops.is_enabled(hw);
}

static const struct clk_ops lpc18xx_ccu_gate_ops = {
        .enable         = lpc18xx_ccu_gate_enable,
        .disable        = lpc18xx_ccu_gate_disable,
        .is_enabled     = lpc18xx_ccu_gate_is_enabled,
};

static void lpc18xx_ccu_register_branch_gate_div(struct lpc18xx_clk_branch *branch,
                                                 void __iomem *reg_base,
                                                 const char *parent)
{
        const struct clk_ops *div_ops = NULL;
        struct clk_divider *div = NULL;
        struct clk_hw *div_hw = NULL;

        if (branch->flags & CCU_BRANCH_HAVE_DIV2) {
                div = kzalloc_obj(*div);
                if (!div)
                        return;

                div->reg = branch->offset + reg_base;
                div->flags = CLK_DIVIDER_READ_ONLY;
                div->shift = 27;
                div->width = 1;

                div_hw = &div->hw;
                div_ops = &clk_divider_ro_ops;
        }

        branch->gate.reg = branch->offset + reg_base;
        branch->gate.bit_idx = 0;

        branch->clk = clk_register_composite(NULL, branch->name, &parent, 1,
                                             NULL, NULL,
                                             div_hw, div_ops,
                                             &branch->gate.hw, &lpc18xx_ccu_gate_ops, 0);
        if (IS_ERR(branch->clk)) {
                kfree(div);
                pr_warn("%s: failed to register %s\n", __func__, branch->name);
                return;
        }

        /* Grab essential branch clocks for CPU and SDRAM */
        switch (branch->offset) {
        case CLK_CPU_EMC:
        case CLK_CPU_CORE:
        case CLK_CPU_CREG:
        case CLK_CPU_EMCDIV:
                clk_prepare_enable(branch->clk);
        }
}

static void lpc18xx_ccu_register_branch_clks(void __iomem *reg_base,
                                             const char *base_name)
{
        const char *parent = base_name;
        int i;

        for (i = 0; i < ARRAY_SIZE(clk_branches); i++) {
                if (strcmp(clk_branches[i].base_name, base_name))
                        continue;

                lpc18xx_ccu_register_branch_gate_div(&clk_branches[i], reg_base,
                                                     parent);

                if (clk_branches[i].flags & CCU_BRANCH_IS_BUS)
                        parent = clk_branches[i].name;
        }
}

static void __init lpc18xx_ccu_init(struct device_node *np)
{
        struct lpc18xx_branch_clk_data *clk_data;
        void __iomem *reg_base;
        int i, ret;

        reg_base = of_iomap(np, 0);
        if (!reg_base) {
                pr_warn("%s: failed to map address range\n", __func__);
                return;
        }

        clk_data = kzalloc_obj(*clk_data);
        if (!clk_data) {
                iounmap(reg_base);
                return;
        }

        clk_data->num = of_property_count_strings(np, "clock-names");
        clk_data->name = kcalloc(clk_data->num, sizeof(char *), GFP_KERNEL);
        if (!clk_data->name) {
                iounmap(reg_base);
                kfree(clk_data);
                return;
        }

        for (i = 0; i < clk_data->num; i++) {
                ret = of_property_read_string_index(np, "clock-names", i,
                                                    &clk_data->name[i]);
                if (ret) {
                        pr_warn("%s: failed to get clock name at idx %d\n",
                                __func__, i);
                        continue;
                }

                lpc18xx_ccu_register_branch_clks(reg_base, clk_data->name[i]);
        }

        of_clk_add_provider(np, lpc18xx_ccu_branch_clk_get, clk_data);
}
CLK_OF_DECLARE(lpc18xx_ccu, "nxp,lpc1850-ccu", lpc18xx_ccu_init);