clk: add lpc18xx ccu clk driver

Add driver for NXP LPC18xx/43xx Clock Control Unit (CCU). The CCU
provides fine grained gating of most clocks present in the SoC.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>

2 files changed, 294 insertions, 0 deletions

diff --git a/drivers/clk/nxp/Makefile b/drivers/clk/nxp/Makefile
index aca9d3e..7f608b0 100644
--- a/drivers/clk/nxp/Makefile
+++ b/drivers/clk/nxp/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_ARCH_LPC18XX)	+= clk-lpc18xx-cgu.o
+obj-$(CONFIG_ARCH_LPC18XX)	+= clk-lpc18xx-ccu.o
diff --git a/drivers/clk/nxp/clk-lpc18xx-ccu.c b/drivers/clk/nxp/clk-lpc18xx-ccu.c
new file mode 100644
index 0000000..eeaee97
--- /dev/null
+++ b/drivers/clk/nxp/clk-lpc18xx-ccu.c
@@ -0,0 +1,293 @@
+/*
+ * Clk driver for NXP LPC18xx/LPC43xx Clock Control Unit (CCU)
+ *
+ * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
+ *
+ * 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.h>
+#include <linux/clk-provider.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)
+
+#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
+
+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 = clk_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 squence 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;
+		clk_writel(val, gate->reg);
+
+		val &= ~LPC18XX_CCU_RUN;
+	}
+
+	clk_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)
+{
+	struct clk_gate *gate = to_clk_gate(hw);
+
+	return clk_readl(gate->reg) & LPC18XX_CCU_RUN;
+}
+
+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(sizeof(*div), GFP_KERNEL);
+		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_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(sizeof(*clk_data), GFP_KERNEL);
+	if (!clk_data)
+		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) {
+		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);