[PATCH 12/43] clk: ep93xx: add DT support for Cirrus EP93xx

[Nikita Shubin <nikita.shubin@maquefel.me>]

This is a rewrite of EP93xx timer driver in
arch/arm/mach-ep93xx/clock.c trying to do everything
the device tree way:

- convert to syscon driver
- provide clock acces via of

Co-developed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
---

Notes:
    rfc->v0
    Linus Walleij:
    - renamed all __underscore
    
    Alexander Sverdlin:
    - "Logick" -> "Logic"
    
    Changes by Alexander Sverdlin:
    - remove pr_info
    - DIV_ROUND_UP_ULL -> DIV_ROUND_CLOSEST
    - fix zeroing bitfield in ep93xx_div_set_rate
    - add sanity check for EP93XX_SYSCON_CHIPID_ID
    - use bit index for DMA clock's
    - ep93xx_clk_register_gate() takes bit index, not mask
    - remove redundant define
    - use DIV_ROUND_CLOSEST() everywhere to achieve frequencies closer to those
      requested
    - Add the forgotten configuration from the deleted
      arch/arm/mach-ep93xx/core.c

 drivers/clk/Kconfig      |   8 +
 drivers/clk/Makefile     |   1 +
 drivers/clk/clk-ep93xx.c | 880 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 889 insertions(+)
 create mode 100644 drivers/clk/clk-ep93xx.c

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 1eef05bb1f99..d3ad975b688e 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -436,6 +436,14 @@ config COMMON_CLK_K210
 	help
 	  Support for the Canaan Kendryte K210 RISC-V SoC clocks.
 
+config COMMON_CLK_EP93XX
+	bool "Clock driver for Cirrus Logic ep93xx SoC"
+	depends on ARCH_EP93XX || COMPILE_TEST
+	select MFD_SYSCON
+	select REGMAP
+	help
+	 This driver supports the SoC clocks on the Cirrus Logic ep93xx.
+
 source "drivers/clk/actions/Kconfig"
 source "drivers/clk/analogbits/Kconfig"
 source "drivers/clk/baikal-t1/Kconfig"
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index e3ca0d058a25..deec25ffd004 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_COMMON_CLK_CDCE706)	+= clk-cdce706.o
 obj-$(CONFIG_COMMON_CLK_CDCE925)	+= clk-cdce925.o
 obj-$(CONFIG_ARCH_CLPS711X)		+= clk-clps711x.o
 obj-$(CONFIG_COMMON_CLK_CS2000_CP)	+= clk-cs2000-cp.o
+obj-$(CONFIG_COMMON_CLK_EP93XX)		+= clk-ep93xx.o
 obj-$(CONFIG_ARCH_SPARX5)		+= clk-sparx5.o
 obj-$(CONFIG_COMMON_CLK_EN7523)		+= clk-en7523.o
 obj-$(CONFIG_COMMON_CLK_FIXED_MMIO)	+= clk-fixed-mmio.o
diff --git a/drivers/clk/clk-ep93xx.c b/drivers/clk/clk-ep93xx.c
new file mode 100644
index 000000000000..e5913fc4c39b
--- /dev/null
+++ b/drivers/clk/clk-ep93xx.c
@@ -0,0 +1,880 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Clock control for Cirrus EP93xx chips.
+ * Copyright (C) 2021 Nikita Shubin <nikita.shubin@maquefel.me>
+ *
+ * Based on a rewrite of arch/arm/mach-ep93xx/clock.c:
+ * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
+ */
+#define pr_fmt(fmt) "ep93xx " KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/soc/cirrus/ep93xx.h>
+#include <dt-bindings/clock/cirrus,ep93xx-clock.h>
+
+#include <asm/div64.h>
+
+#define EP93XX_EXT_CLK_RATE		14745600
+#define EP93XX_EXT_RTC_RATE		32768
+
+#define EP93XX_SYSCON_POWER_STATE	0x00
+#define EP93XX_SYSCON_PWRCNT		0x04
+#define EP93XX_SYSCON_PWRCNT_UARTBAUD	BIT(29)
+#define EP93XX_SYSCON_PWRCNT_USH_EN	28
+#define EP93XX_SYSCON_PWRCNT_DMA_M2M1	27
+#define EP93XX_SYSCON_PWRCNT_DMA_M2M0	26
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P8	25
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P9	24
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P6	23
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P7	22
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P4	21
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P5	20
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P2	19
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P3	18
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P0	17
+#define EP93XX_SYSCON_PWRCNT_DMA_M2P1	16
+#define EP93XX_SYSCON_CLKSET1		0x20
+#define EP93XX_SYSCON_CLKSET1_NBYP1	BIT(23)
+#define EP93XX_SYSCON_CLKSET2		0x24
+#define EP93XX_SYSCON_CLKSET2_NBYP2	BIT(19)
+#define EP93XX_SYSCON_CLKSET2_PLL2_EN	BIT(18)
+#define EP93XX_SYSCON_DEVCFG		0x80
+#define EP93XX_SYSCON_DEVCFG_U3EN	24
+#define EP93XX_SYSCON_DEVCFG_U2EN	20
+#define EP93XX_SYSCON_DEVCFG_U1EN	18
+#define EP93XX_SYSCON_VIDCLKDIV		0x84
+#define EP93XX_SYSCON_CLKDIV_ENABLE	15
+#define EP93XX_SYSCON_CLKDIV_ESEL	BIT(14)
+#define EP93XX_SYSCON_CLKDIV_PSEL	BIT(13)
+#define EP93XX_SYSCON_CLKDIV_PDIV_SHIFT	8
+#define EP93XX_SYSCON_I2SCLKDIV		0x8c
+#define EP93XX_SYSCON_I2SCLKDIV_SENA	31
+#define EP93XX_SYSCON_I2SCLKDIV_ORIDE	BIT(29)
+#define EP93XX_SYSCON_I2SCLKDIV_SPOL	BIT(19)
+#define EP93XX_I2SCLKDIV_SDIV		(1 << 16)
+#define EP93XX_I2SCLKDIV_LRDIV32	(0 << 17)
+#define EP93XX_I2SCLKDIV_LRDIV64	(1 << 17)
+#define EP93XX_I2SCLKDIV_LRDIV128	(2 << 17)
+#define EP93XX_I2SCLKDIV_LRDIV_MASK	(3 << 17)
+#define EP93XX_SYSCON_KEYTCHCLKDIV	0x90
+#define EP93XX_SYSCON_KEYTCHCLKDIV_TSEN	31
+#define EP93XX_SYSCON_KEYTCHCLKDIV_ADIV	16
+#define EP93XX_SYSCON_KEYTCHCLKDIV_KEN	15
+#define EP93XX_SYSCON_KEYTCHCLKDIV_KDIV	0
+#define EP93XX_SYSCON_CHIPID		0x94
+#define EP93XX_SYSCON_CHIPID_ID		0x9213
+
+static DEFINE_SPINLOCK(clk_lock);
+static struct regmap *ep93xx_map;
+#define ep93xx_regmap_read(reg, val) regmap_read(ep93xx_map, reg, val)
+
+/* Keeps track of all clocks */
+static struct clk_hw_onecell_data *ep93xx_clk_data;
+
+static char fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
+static char hclk_divisors[] = { 1, 2, 4, 5, 6, 8, 16, 32 };
+static char pclk_divisors[] = { 1, 2, 4, 8 };
+
+static char adc_divisors[] = { 16, 4 };
+static char sclk_divisors[] = { 2, 4 };
+static char lrclk_divisors[] = { 32, 64, 128 };
+
+static const char * const mux_parents[] = {
+	"xtali",
+	"pll1",
+	"pll2"
+};
+
+/*
+ * PLL rate = 14.7456 MHz * (X1FBD + 1) * (X2FBD + 1) / (X2IPD + 1) / 2^PS
+ */
+static unsigned long calc_pll_rate(unsigned long long rate, u32 config_word)
+{
+	int i;
+
+	rate *= ((config_word >> 11) & 0x1f) + 1;		/* X1FBD */
+	rate *= ((config_word >> 5) & 0x3f) + 1;		/* X2FBD */
+	do_div(rate, (config_word & 0x1f) + 1);			/* X2IPD */
+	for (i = 0; i < ((config_word >> 16) & 3); i++)		/* PS */
+		rate >>= 1;
+
+	return (unsigned long)rate;
+}
+
+struct clk_psc {
+	struct clk_hw hw;
+	unsigned int reg;
+	u8 bit_idx;
+	u32 mask;
+	u8 shift;
+	u8 width;
+	char *div;
+	u8 num_div;
+	spinlock_t *lock;
+};
+
+#define to_clk_psc(_hw) container_of(_hw, struct clk_psc, hw)
+
+static int ep93xx_clk_is_enabled(struct clk_hw *hw)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	u32 val;
+
+	ep93xx_regmap_read(psc->reg, &val);
+
+	return (val & BIT(psc->bit_idx)) ? 1 : 0;
+}
+
+static int ep93xx_clk_enable(struct clk_hw *hw)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	unsigned long flags = 0;
+	u32 val;
+
+	if (psc->lock)
+		spin_lock_irqsave(psc->lock, flags);
+
+	ep93xx_regmap_read(psc->reg, &val);
+	val |= BIT(psc->bit_idx);
+
+	ep93xx_syscon_swlocked_write(val, psc->reg);
+
+	if (psc->lock)
+		spin_unlock_irqrestore(psc->lock, flags);
+
+	return 0;
+}
+
+static void ep93xx_clk_disable(struct clk_hw *hw)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	unsigned long flags = 0;
+	u32 val;
+
+	if (psc->lock)
+		spin_lock_irqsave(psc->lock, flags);
+
+	ep93xx_regmap_read(psc->reg, &val);
+	val &= ~BIT(psc->bit_idx);
+
+	ep93xx_syscon_swlocked_write(val, psc->reg);
+
+	if (psc->lock)
+		spin_unlock_irqrestore(psc->lock, flags);
+}
+
+static const struct clk_ops clk_ep93xx_gate_ops = {
+	.enable = ep93xx_clk_enable,
+	.disable = ep93xx_clk_disable,
+	.is_enabled = ep93xx_clk_is_enabled,
+};
+
+static struct clk_hw *ep93xx_clk_register_gate(const char *name,
+				    const char *parent_name,
+				    unsigned int reg,
+				    u8 bit_idx)
+{
+	struct clk_init_data init;
+	struct clk_psc *psc;
+	struct clk *clk;
+
+	psc = kzalloc(sizeof(*psc), GFP_KERNEL);
+	if (!psc)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_ep93xx_gate_ops;
+	init.flags = CLK_SET_RATE_PARENT;
+	init.parent_names = (parent_name ? &parent_name : NULL);
+	init.num_parents = (parent_name ? 1 : 0);
+
+	psc->reg = reg;
+	psc->bit_idx = bit_idx;
+	psc->hw.init = &init;
+	psc->lock = &clk_lock;
+
+	clk = clk_register(NULL, &psc->hw);
+	if (IS_ERR(clk)) {
+		kfree(psc);
+		return ERR_CAST(clk);
+	}
+
+	return &psc->hw;
+}
+
+static u8 ep93xx_mux_get_parent(struct clk_hw *hw)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	u32 val;
+
+	ep93xx_regmap_read(psc->reg, &val);
+	if (!(val & EP93XX_SYSCON_CLKDIV_ESEL))
+		return 0;
+
+	if (!(val & EP93XX_SYSCON_CLKDIV_PSEL))
+		return 1;
+
+	return 2;
+}
+
+static int ep93xx_mux_set_parent_lock(struct clk_hw *hw, u8 index)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	unsigned long flags = 0;
+	u32 val;
+
+	if (index >= ARRAY_SIZE(mux_parents))
+		return -EINVAL;
+
+	if (psc->lock)
+		spin_lock_irqsave(psc->lock, flags);
+
+	ep93xx_regmap_read(psc->reg, &val);
+	val &= ~(EP93XX_SYSCON_CLKDIV_ESEL | EP93XX_SYSCON_CLKDIV_PSEL);
+
+	if (index != 0) {
+		val |= EP93XX_SYSCON_CLKDIV_ESEL;
+		val |= (index - 1) ? EP93XX_SYSCON_CLKDIV_PSEL : 0;
+	}
+
+	ep93xx_syscon_swlocked_write(val, psc->reg);
+
+	if (psc->lock)
+		spin_unlock_irqrestore(psc->lock, flags);
+
+	return 0;
+}
+
+static bool is_best(unsigned long rate, unsigned long now,
+		     unsigned long best)
+{
+	return abs(rate - now) < abs(rate - best);
+}
+
+static int ep93xx_mux_determine_rate(struct clk_hw *hw,
+				struct clk_rate_request *req)
+{
+	unsigned long rate = req->rate;
+	struct clk *parent_best = NULL;
+	unsigned long parent_rate;
+	unsigned long best_rate = 0, actual_rate, mclk_rate;
+	unsigned long parent_rate_best;
+	int div, pdiv;
+	int i;
+
+	/*
+	 * Try the two pll's and the external clock
+	 * Because the valid predividers are 2, 2.5 and 3, we multiply
+	 * all the clocks by 2 to avoid floating point math.
+	 *
+	 * This is based on the algorithm in the ep93xx raster guide:
+	 * http://be-a-maverick.com/en/pubs/appNote/AN269REV1.pdf
+	 *
+	 */
+	for (i = 0; i < ARRAY_SIZE(mux_parents); i++) {
+		struct clk *parent = clk_get_sys(mux_parents[i], NULL);
+
+		parent_rate = clk_get_rate(parent);
+		mclk_rate = parent_rate * 2;
+
+		/* Try each predivider value */
+		for (pdiv = 4; pdiv <= 6; pdiv++) {
+			div = DIV_ROUND_CLOSEST(mclk_rate, rate * pdiv);
+			if (div < 1 || div > 127)
+				continue;
+
+			actual_rate = DIV_ROUND_CLOSEST(mclk_rate, pdiv * div);
+
+			if (is_best(rate, actual_rate, best_rate)) {
+				best_rate = actual_rate;
+				parent_rate_best = parent_rate;
+				parent_best = parent;
+			}
+		}
+	}
+
+	if (!parent_best)
+		return -EINVAL;
+
+	req->best_parent_rate = parent_rate_best;
+	req->best_parent_hw = __clk_get_hw(parent_best);
+	req->rate = best_rate;
+
+	return 0;
+}
+
+static unsigned long ep93xx_ddiv_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	unsigned long rate = 0;
+	u32 val;
+	int pdiv, div;
+
+	ep93xx_regmap_read(psc->reg, &val);
+	pdiv = ((val >> EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) & 0x03);
+	div = val & 0x7f;
+	if (div > 0)
+		rate = DIV_ROUND_CLOSEST(parent_rate * 2, (pdiv + 3) * div);
+
+	return rate;
+}
+
+static int ep93xx_ddiv_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	int pdiv, div, npdiv, ndiv;
+	unsigned long actual_rate, mclk_rate, rate_err = -1;
+	int found = 0;
+	u32 val;
+
+	ep93xx_regmap_read(psc->reg, &val);
+	mclk_rate = parent_rate * 2;
+
+	for (pdiv = 4; pdiv <= 6; pdiv++) {
+		div = DIV_ROUND_CLOSEST(mclk_rate, rate * pdiv);
+		if (div < 1 || div > 127)
+			continue;
+
+		actual_rate = DIV_ROUND_CLOSEST(mclk_rate, pdiv * div);
+
+		if (!found || abs(actual_rate - rate) < rate_err) {
+			npdiv = pdiv - 3;
+			ndiv = div;
+			rate_err = abs(actual_rate - rate);
+			found = 1;
+		}
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	/* Clear old dividers */
+	val &= ~0x37f;
+
+	/* Set the new pdiv and div bits for the new clock rate */
+	val |= (npdiv << EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) | ndiv;
+
+	ep93xx_syscon_swlocked_write(val, psc->reg);
+
+	return 0;
+}
+
+static const struct clk_ops clk_ddiv_ops = {
+	.enable = ep93xx_clk_enable,
+	.disable = ep93xx_clk_disable,
+	.is_enabled = ep93xx_clk_is_enabled,
+	.get_parent = ep93xx_mux_get_parent,
+	.set_parent = ep93xx_mux_set_parent_lock,
+	.determine_rate = ep93xx_mux_determine_rate,
+	.recalc_rate = ep93xx_ddiv_recalc_rate,
+	.set_rate = ep93xx_ddiv_set_rate,
+};
+
+static struct clk_hw *clk_hw_register_ddiv(const char *name,
+					  unsigned int reg,
+					  u8 bit_idx)
+{
+	struct clk_init_data init;
+	struct clk_psc *psc;
+	struct clk *clk;
+
+	psc = kzalloc(sizeof(*psc), GFP_KERNEL);
+	if (!psc)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_ddiv_ops;
+	init.flags = 0;
+	init.parent_names = mux_parents;
+	init.num_parents = ARRAY_SIZE(mux_parents);
+
+	psc->reg = reg;
+	psc->bit_idx = bit_idx;
+	psc->lock = &clk_lock;
+	psc->hw.init = &init;
+
+	clk = clk_register(NULL, &psc->hw);
+	if (IS_ERR(clk)) {
+		kfree(psc);
+		return ERR_CAST(clk);
+	}
+
+	return &psc->hw;
+}
+
+static unsigned long ep93xx_div_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	u32 val;
+	u8 index;
+
+	ep93xx_regmap_read(psc->reg, &val);
+	index = (val & psc->mask) >> psc->shift;
+	if (index > psc->num_div)
+		return 0;
+
+	return DIV_ROUND_CLOSEST(parent_rate, psc->div[index]);
+}
+
+static long ep93xx_div_round_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long *parent_rate)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	unsigned long best = 0, now;
+	bool assigned = false;
+	int i;
+
+	for (i = 0; i < psc->num_div; i++) {
+		if ((rate * psc->div[i]) == *parent_rate)
+			return rate;
+
+		now = DIV_ROUND_CLOSEST(*parent_rate, psc->div[i]);
+
+		if (!assigned || is_best(rate, now, best))
+			best = now;
+		assigned = true;
+	}
+
+	return best;
+}
+
+static int ep93xx_div_set_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long parent_rate)
+{
+	struct clk_psc *psc = to_clk_psc(hw);
+	u32 val;
+	int i;
+
+	ep93xx_regmap_read(psc->reg, &val);
+	val &= ~psc->mask;
+	for (i = 0; i < psc->num_div; i++)
+		if (rate == DIV_ROUND_CLOSEST(parent_rate, psc->div[i])) {
+			val |= i << psc->shift;
+			break;
+		}
+
+	if (i == psc->num_div)
+		return -EINVAL;
+
+	ep93xx_syscon_swlocked_write(val, psc->reg);
+
+	return 0;
+}
+
+static const struct clk_ops ep93xx_div_ops = {
+	.enable = ep93xx_clk_enable,
+	.disable = ep93xx_clk_disable,
+	.is_enabled = ep93xx_clk_is_enabled,
+	.recalc_rate = ep93xx_div_recalc_rate,
+	.round_rate = ep93xx_div_round_rate,
+	.set_rate = ep93xx_div_set_rate,
+};
+
+static struct clk_hw *clk_hw_register_div(const char *name,
+					  const char *parent_name,
+					  unsigned int reg,
+					  u8 enable_bit,
+					  u8 shift,
+					  u8 width,
+					  char *clk_divisors,
+					  u8 num_div)
+{
+	struct clk_init_data init;
+	struct clk_psc *psc;
+	struct clk *clk;
+
+	psc = kzalloc(sizeof(*psc), GFP_KERNEL);
+	if (!psc)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &ep93xx_div_ops;
+	init.flags = 0;
+	init.parent_names = (parent_name ? &parent_name : NULL);
+	init.num_parents = 1;
+
+	psc->reg = reg;
+	psc->bit_idx = enable_bit;
+	psc->mask = GENMASK(shift + width - 1, shift);
+	psc->shift = shift;
+	psc->div = clk_divisors;
+	psc->num_div = num_div;
+	psc->lock = &clk_lock;
+	psc->hw.init = &init;
+
+	clk = clk_register(NULL, &psc->hw);
+	if (IS_ERR(clk)) {
+		kfree(psc);
+		return ERR_CAST(clk);
+	}
+
+	return &psc->hw;
+}
+
+struct ep93xx_gate {
+	unsigned int idx;
+	unsigned int bit;
+	const char *dev_id;
+	const char *con_id;
+};
+
+static struct ep93xx_gate ep93xx_uarts[] = {
+	{EP93XX_CLK_UART1, EP93XX_SYSCON_DEVCFG_U1EN, "apb:uart1", NULL},
+	{EP93XX_CLK_UART2, EP93XX_SYSCON_DEVCFG_U2EN, "apb:uart2", NULL},
+	{EP93XX_CLK_UART3, EP93XX_SYSCON_DEVCFG_U3EN, "apb:uart3", NULL},
+};
+
+static void ep93xx_uart_clock_init(void)
+{
+	unsigned int i;
+	struct clk_hw *hw;
+	u32 val;
+	unsigned int clk_uart_div;
+
+	ep93xx_regmap_read(EP93XX_SYSCON_PWRCNT, &val);
+	if (val & EP93XX_SYSCON_PWRCNT_UARTBAUD)
+		clk_uart_div = 1;
+	else
+		clk_uart_div = 2;
+
+	hw = clk_hw_register_fixed_factor(NULL, "uart", "xtali", 0, 1, clk_uart_div);
+	ep93xx_clk_data->hws[EP93XX_CLK_UART] = hw;
+
+	/* parenting uart gate clocks to uart clock */
+	for (i = 0; i < ARRAY_SIZE(ep93xx_uarts); i++) {
+		hw = ep93xx_clk_register_gate(ep93xx_uarts[i].dev_id,
+					"uart",
+					EP93XX_SYSCON_DEVCFG,
+					ep93xx_uarts[i].bit);
+
+		ep93xx_clk_data->hws[ep93xx_uarts[i].idx] = hw;
+	}
+}
+
+static struct ep93xx_gate ep93xx_dmas[] = {
+	{EP93XX_CLK_M2P0, EP93XX_SYSCON_PWRCNT_DMA_M2P0, NULL, "m2p0"},
+	{EP93XX_CLK_M2P1, EP93XX_SYSCON_PWRCNT_DMA_M2P1, NULL, "m2p1"},
+	{EP93XX_CLK_M2P2, EP93XX_SYSCON_PWRCNT_DMA_M2P2, NULL, "m2p2"},
+	{EP93XX_CLK_M2P3, EP93XX_SYSCON_PWRCNT_DMA_M2P3, NULL, "m2p3"},
+	{EP93XX_CLK_M2P4, EP93XX_SYSCON_PWRCNT_DMA_M2P4, NULL, "m2p4"},
+	{EP93XX_CLK_M2P5, EP93XX_SYSCON_PWRCNT_DMA_M2P5, NULL, "m2p5"},
+	{EP93XX_CLK_M2P6, EP93XX_SYSCON_PWRCNT_DMA_M2P6, NULL, "m2p6"},
+	{EP93XX_CLK_M2P7, EP93XX_SYSCON_PWRCNT_DMA_M2P7, NULL, "m2p7"},
+	{EP93XX_CLK_M2P8, EP93XX_SYSCON_PWRCNT_DMA_M2P8, NULL, "m2p8"},
+	{EP93XX_CLK_M2P9, EP93XX_SYSCON_PWRCNT_DMA_M2P9, NULL, "m2p9"},
+	{EP93XX_CLK_M2M0, EP93XX_SYSCON_PWRCNT_DMA_M2M0, NULL, "m2m0"},
+	{EP93XX_CLK_M2M1, EP93XX_SYSCON_PWRCNT_DMA_M2M1, NULL, "m2m1"},
+};
+
+static void ep93xx_dma_clock_init(void __iomem *base)
+{
+	int i;
+	struct clk_hw *hw;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(ep93xx_dmas); i++) {
+		hw = clk_hw_register_gate(NULL, ep93xx_dmas[i].con_id,
+					"hclk", 0,
+					base + EP93XX_SYSCON_PWRCNT,
+					ep93xx_dmas[i].bit,
+					0,
+					&clk_lock);
+
+		ret = clk_hw_register_clkdev(hw, ep93xx_dmas[i].con_id, NULL);
+		if (ret) {
+			pr_err("%s: failed to register lookup %s\n",
+			       __func__, ep93xx_dmas[i].con_id);
+			continue;
+		}
+
+		ep93xx_clk_data->hws[ep93xx_dmas[i].idx] = hw;
+	}
+}
+
+static int ep93xx_clk_probe(struct platform_device *pdev)
+{
+	void __iomem *base;
+	unsigned int clk_usb_div;
+	unsigned long clk_spi_div;
+	struct clk_hw *hw;
+	struct device *dev = &pdev->dev;
+	u32 value;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	ep93xx_regmap_read(EP93XX_SYSCON_CLKSET2, &value);
+	clk_usb_div = (((value >> 28) & 0xf) + 1);
+	hw = clk_hw_register_fixed_factor(NULL, "usb_clk", "pll2", 0, 1, clk_usb_div);
+	hw = clk_hw_register_gate(NULL, "ohci-platform",
+				"usb_clk", 0,
+				base + EP93XX_SYSCON_PWRCNT,
+				EP93XX_SYSCON_PWRCNT_USH_EN,
+				0,
+				&clk_lock);
+	clk_hw_register_clkdev(hw, NULL, "ohci-platform");
+	ep93xx_clk_data->hws[EP93XX_CLK_USB] = hw;
+
+	/*
+	 * EP93xx SSP clock rate was doubled in version E2. For more information
+	 * see:
+	 *     http://www.cirrus.com/en/pubs/appNote/AN273REV4.pdf
+	 */
+	clk_spi_div = 1;
+	if (ep93xx_chip_revision() < EP93XX_CHIP_REV_E2)
+		clk_spi_div = 2;
+	hw = clk_hw_register_fixed_factor(NULL, "ep93xx-spi.0", "xtali", 0, 1, clk_spi_div);
+	clk_hw_register_clkdev(hw, NULL, "ep93xx-spi.0");
+	ep93xx_clk_data->hws[EP93XX_CLK_SPI] = hw;
+
+	/* pwm clock */
+	hw = clk_hw_register_fixed_factor(NULL, "pwm_clk", "xtali", 0, 1, 1);
+	clk_hw_register_clkdev(hw, "pwm_clk", NULL);
+	ep93xx_clk_data->hws[EP93XX_CLK_PWM] = hw;
+
+	ep93xx_uart_clock_init();
+
+	/* touchscreen/adc clock */
+	hw = clk_hw_register_div("ep93xx-adc",
+				"xtali",
+				EP93XX_SYSCON_KEYTCHCLKDIV,
+				EP93XX_SYSCON_KEYTCHCLKDIV_TSEN,
+				EP93XX_SYSCON_KEYTCHCLKDIV_ADIV,
+				1,
+				adc_divisors,
+				ARRAY_SIZE(adc_divisors));
+
+	clk_hw_register_clkdev(hw, NULL, "ep93xx-adc");
+	ep93xx_clk_data->hws[EP93XX_CLK_ADC] = hw;
+
+	/* keypad clock */
+	hw = clk_hw_register_div("ep93xx-keypad",
+				"xtali",
+				EP93XX_SYSCON_KEYTCHCLKDIV,
+				EP93XX_SYSCON_KEYTCHCLKDIV_KEN,
+				EP93XX_SYSCON_KEYTCHCLKDIV_KDIV,
+				1,
+				adc_divisors,
+				ARRAY_SIZE(adc_divisors));
+
+	clk_hw_register_clkdev(hw, NULL, "ep93xx-keypad");
+	ep93xx_clk_data->hws[EP93XX_CLK_KEYPAD] = hw;
+
+	/* On reset PDIV and VDIV is set to zero, while PDIV zero
+	 * means clock disable, VDIV shouldn't be zero.
+	 * So i set both dividers to minimum.
+	 */
+	/* ENA - Enable CLK divider. */
+	/* PDIV - 00 - Disable clock */
+	/* VDIV - at least 2 */
+	/* Check and enable video clk registers */
+	ep93xx_regmap_read(EP93XX_SYSCON_VIDCLKDIV, &value);
+	value |= (1 << EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) | 2;
+	ep93xx_syscon_swlocked_write(value, EP93XX_SYSCON_VIDCLKDIV);
+
+	/* check and enable i2s clk registers */
+	ep93xx_regmap_read(EP93XX_SYSCON_I2SCLKDIV, &value);
+	value |= (1 << EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) | 2;
+	/*
+	 * Override the SAI_MSTR_CLK_CFG from the I2S block and use the
+	 * I2SClkDiv Register settings. LRCLK transitions on the falling SCLK
+	 * edge.
+	 */
+	value |= EP93XX_SYSCON_I2SCLKDIV_ORIDE | EP93XX_SYSCON_I2SCLKDIV_SPOL;
+	ep93xx_syscon_swlocked_write(value, EP93XX_SYSCON_I2SCLKDIV);
+
+	/* video clk */
+	hw = clk_hw_register_ddiv("ep93xx-fb",
+				EP93XX_SYSCON_VIDCLKDIV,
+				EP93XX_SYSCON_CLKDIV_ENABLE);
+
+	clk_hw_register_clkdev(hw, NULL, "ep93xx-fb");
+	ep93xx_clk_data->hws[EP93XX_CLK_VIDEO] = hw;
+
+	/* i2s clk */
+	hw = clk_hw_register_ddiv("mclk",
+				EP93XX_SYSCON_I2SCLKDIV,
+				EP93XX_SYSCON_CLKDIV_ENABLE);
+
+	clk_hw_register_clkdev(hw, "mclk", "ep93xx-i2s");
+	ep93xx_clk_data->hws[EP93XX_CLK_I2S_MCLK] = hw;
+
+	/* i2s sclk */
+#define EP93XX_I2SCLKDIV_SDIV_SHIFT	16
+#define EP93XX_I2SCLKDIV_SDIV_WIDTH	1
+	hw = clk_hw_register_div("sclk",
+				"mclk",
+				EP93XX_SYSCON_I2SCLKDIV,
+				EP93XX_SYSCON_I2SCLKDIV_SENA,
+				EP93XX_I2SCLKDIV_SDIV_SHIFT,
+				EP93XX_I2SCLKDIV_SDIV_WIDTH,
+				sclk_divisors,
+				ARRAY_SIZE(sclk_divisors));
+
+	clk_hw_register_clkdev(hw, "sclk", "ep93xx-i2s");
+	ep93xx_clk_data->hws[EP93XX_CLK_I2S_SCLK] = hw;
+
+	/* i2s lrclk */
+#define EP93XX_I2SCLKDIV_LRDIV32_SHIFT	17
+#define EP93XX_I2SCLKDIV_LRDIV32_WIDTH	2
+	hw = clk_hw_register_div("lrclk",
+				"sclk",
+				EP93XX_SYSCON_I2SCLKDIV,
+				EP93XX_SYSCON_I2SCLKDIV_SENA,
+				EP93XX_I2SCLKDIV_LRDIV32_SHIFT,
+				EP93XX_I2SCLKDIV_LRDIV32_WIDTH,
+				lrclk_divisors,
+				ARRAY_SIZE(lrclk_divisors));
+
+	clk_hw_register_clkdev(hw, "lrclk", "ep93xx-i2s");
+	ep93xx_clk_data->hws[EP93XX_CLK_I2S_LRCLK] = hw;
+
+	/* IrDa clk uses same pattern but no init code presents in original clock driver */
+	return 0;
+}
+
+static const struct of_device_id ep93xx_clk_dt_ids[] = {
+	{ .compatible = "cirrus,ep9301-syscon", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver ep93xx_clk_driver = {
+	.probe  = ep93xx_clk_probe,
+	.driver = {
+		.name = "ep93xx-clk",
+		.of_match_table = ep93xx_clk_dt_ids,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(ep93xx_clk_driver);
+
+static void __init ep93xx_clock_init(struct device_node *np)
+{
+	void __iomem *base;
+	int i;
+	int ret;
+	u32 value;
+	struct clk_hw *hw;
+	unsigned long clk_pll1_rate;
+	unsigned long clk_f_rate;
+	unsigned long clk_h_rate;
+	unsigned long clk_p_rate;
+	unsigned long clk_pll2_rate;
+	unsigned int clk_f_div;
+	unsigned int clk_h_div;
+	unsigned int clk_p_div;
+
+	ep93xx_clk_data = kzalloc(struct_size(ep93xx_clk_data, hws,
+				EP93XX_NUM_CLKS),
+				GFP_KERNEL);
+
+	if (!ep93xx_clk_data)
+		return;
+
+	/*
+	 * This way all clock fetched before the platform device probes,
+	 * except those we assign here for early use, will be deferred.
+	 */
+	for (i = 0; i < EP93XX_NUM_CLKS; i++)
+		ep93xx_clk_data->hws[i] = ERR_PTR(-EPROBE_DEFER);
+
+	base = of_iomap(np, 0);
+	/* Remap the system controller for the exclusive register */
+	if (IS_ERR(base)) {
+		pr_err("failed to map base\n");
+		return;
+	}
+
+	ep93xx_map = syscon_node_to_regmap(np);
+	if (IS_ERR(ep93xx_map)) {
+		pr_err("no syscon regmap\n");
+		return;
+	}
+
+	/*
+	 * We check that the regmap works on this very first access,
+	 * but as this is an MMIO-backed regmap, subsequent regmap
+	 * access is not going to fail and we skip error checks from
+	 * this point.
+	 */
+	ret = ep93xx_regmap_read(EP93XX_SYSCON_CHIPID, &value);
+	if (ret || (value & 0xffff) != EP93XX_SYSCON_CHIPID_ID) {
+		pr_err("failed to read global status register\n");
+		return;
+	}
+
+	hw = clk_hw_register_fixed_rate(NULL, "xtali", NULL, 0, EP93XX_EXT_CLK_RATE);
+	clk_hw_register_clkdev(hw, NULL, "xtali");
+
+	/* Determine the bootloader configured pll1 rate */
+	ep93xx_regmap_read(EP93XX_SYSCON_CLKSET1, &value);
+	if (!(value & EP93XX_SYSCON_CLKSET1_NBYP1))
+		clk_pll1_rate = EP93XX_EXT_CLK_RATE;
+	else
+		clk_pll1_rate = calc_pll_rate(EP93XX_EXT_CLK_RATE, value);
+
+	hw = clk_hw_register_fixed_rate(NULL, "pll1", "xtali", 0, clk_pll1_rate);
+	clk_hw_register_clkdev(hw, NULL, "pll1");
+	ep93xx_clk_data->hws[EP93XX_CLK_PLL1] = hw;
+
+	/* Initialize the pll1 derived clocks */
+	clk_f_div = fclk_divisors[(value >> 25) & 0x7];
+	clk_h_div = hclk_divisors[(value >> 20) & 0x7];
+	clk_p_div = pclk_divisors[(value >> 18) & 0x3];
+
+	hw = clk_hw_register_fixed_factor(NULL, "fclk", "pll1", 0, 1, clk_f_div);
+	clk_f_rate = clk_get_rate(hw->clk);
+	ep93xx_clk_data->hws[EP93XX_CLK_FCLK] = hw;
+	hw = clk_hw_register_fixed_factor(NULL, "hclk", "pll1", 0, 1, clk_h_div);
+	clk_h_rate = clk_get_rate(hw->clk);
+	ep93xx_clk_data->hws[EP93XX_CLK_HCLK] = hw;
+	hw = clk_hw_register_fixed_factor(NULL, "pclk", "hclk", 0, 1, clk_p_div);
+	clk_p_rate = clk_get_rate(hw->clk);
+	ep93xx_clk_data->hws[EP93XX_CLK_PCLK] = hw;
+
+	clk_hw_register_clkdev(hw, "apb_pclk", NULL);
+
+	ep93xx_dma_clock_init(base);
+
+	/* Determine the bootloader configured pll2 rate */
+	ep93xx_regmap_read(EP93XX_SYSCON_CLKSET2, &value);
+	if (!(value & EP93XX_SYSCON_CLKSET2_NBYP2))
+		clk_pll2_rate = EP93XX_EXT_CLK_RATE;
+	else if (value & EP93XX_SYSCON_CLKSET2_PLL2_EN)
+		clk_pll2_rate = calc_pll_rate(EP93XX_EXT_CLK_RATE, value);
+	else
+		clk_pll2_rate = 0;
+
+	hw = clk_hw_register_fixed_rate(NULL, "pll2", "xtali", 0, clk_pll2_rate);
+	ep93xx_clk_data->hws[EP93XX_CLK_PLL2] = hw;
+	clk_hw_register_clkdev(hw, NULL, "pll2");
+
+	ep93xx_clk_data->num = EP93XX_NUM_CLKS;
+	of_clk_add_hw_provider(np, of_clk_hw_onecell_get, ep93xx_clk_data);
+
+	pr_info("PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
+		clk_pll1_rate / 1000000, clk_pll2_rate / 1000000);
+	pr_info("FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
+		clk_f_rate / 1000000, clk_h_rate / 1000000,
+		clk_p_rate / 1000000);
+}
+CLK_OF_DECLARE_DRIVER(ep93xx_cc, "cirrus,ep9301-syscon", ep93xx_clock_init);
-- 
2.39.2