clk: stm32: Add clock driver for STM32F4[23]xxx devices

The driver supports decoding and statically modelling PLL state (i.e.
we inherit state from bootloader) and provides support for all
peripherals that support simple one-bit gated clocks. The covers all
peripherals whose clocks come from the AHB, APB1 or APB2 buses.

It has been tested on an STM32F429I-Discovery board. The clock counts
for TIM2, USART1 and SYSTICK are all set correctly and the wall clock
looks OK when checked with a stopwatch. I have also tested a prototype
driver for the RNG hardware. The RNG clock is correctly enabled by the
framework (also did inverse test and proved that by changing DT to
configure the wrong clock bit then we observe the RNG driver to fail).

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
[sboyd@codeaurora.org: Silence sparse warnings]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

2 files changed, 381 insertions, 0 deletions

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 256977ed050a..fc789a07cb5f 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
 obj-$(CONFIG_COMMON_CLK_SI5351)		+= clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI570)		+= clk-si570.o
 obj-$(CONFIG_COMMON_CLK_CDCE925)	+= clk-cdce925.o
+obj-$(CONFIG_ARCH_STM32)		+= clk-stm32f4.o
 obj-$(CONFIG_CLK_TWL6040)		+= clk-twl6040.o
 obj-$(CONFIG_ARCH_U300)			+= clk-u300.o
 obj-$(CONFIG_ARCH_VT8500)		+= clk-vt8500.o
diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
new file mode 100644
index 000000000000..b9b12a742970
--- /dev/null
+++ b/drivers/clk/clk-stm32f4.c
@@ -0,0 +1,380 @@
+/*
+ * Author: Daniel Thompson <daniel.thompson@linaro.org>
+ *
+ * Inspired by clk-asm9260.c .
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#define STM32F4_RCC_PLLCFGR		0x04
+#define STM32F4_RCC_CFGR		0x08
+#define STM32F4_RCC_AHB1ENR		0x30
+#define STM32F4_RCC_AHB2ENR		0x34
+#define STM32F4_RCC_AHB3ENR		0x38
+#define STM32F4_RCC_APB1ENR		0x40
+#define STM32F4_RCC_APB2ENR		0x44
+
+struct stm32f4_gate_data {
+	u8	offset;
+	u8	bit_idx;
+	const char *name;
+	const char *parent_name;
+	unsigned long flags;
+};
+
+static const struct stm32f4_gate_data stm32f4_gates[] __initconst = {
+	{ STM32F4_RCC_AHB1ENR,  0,	"gpioa",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  1,	"gpiob",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  2,	"gpioc",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  3,	"gpiod",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  4,	"gpioe",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  5,	"gpiof",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  6,	"gpiog",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  7,	"gpioh",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  8,	"gpioi",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR,  9,	"gpioj",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 10,	"gpiok",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 12,	"crc",		"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 18,	"bkpsra",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 20,	"ccmdatam",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 21,	"dma1",		"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 22,	"dma2",		"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 23,	"dma2d",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 25,	"ethmac",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 26,	"ethmactx",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 27,	"ethmacrx",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 28,	"ethmacptp",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 29,	"otghs",	"ahb_div" },
+	{ STM32F4_RCC_AHB1ENR, 30,	"otghsulpi",	"ahb_div" },
+
+	{ STM32F4_RCC_AHB2ENR,  0,	"dcmi",		"ahb_div" },
+	{ STM32F4_RCC_AHB2ENR,  4,	"cryp",		"ahb_div" },
+	{ STM32F4_RCC_AHB2ENR,  5,	"hash",		"ahb_div" },
+	{ STM32F4_RCC_AHB2ENR,  6,	"rng",		"pll48" },
+	{ STM32F4_RCC_AHB2ENR,  7,	"otgfs",	"pll48" },
+
+	{ STM32F4_RCC_AHB3ENR,  0,	"fmc",		"ahb_div",
+		CLK_IGNORE_UNUSED },
+
+	{ STM32F4_RCC_APB1ENR,  0,	"tim2",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  1,	"tim3",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  2,	"tim4",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  3,	"tim5",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  4,	"tim6",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  5,	"tim7",		"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  6,	"tim12",	"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  7,	"tim13",	"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR,  8,	"tim14",	"apb1_mul" },
+	{ STM32F4_RCC_APB1ENR, 11,	"wwdg",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 14,	"spi2",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 15,	"spi3",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 17,	"uart2",	"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 18,	"uart3",	"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 19,	"uart4",	"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 20,	"uart5",	"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 21,	"i2c1",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 22,	"i2c2",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 23,	"i2c3",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 25,	"can1",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 26,	"can2",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 28,	"pwr",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 29,	"dac",		"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 30,	"uart7",	"apb1_div" },
+	{ STM32F4_RCC_APB1ENR, 31,	"uart8",	"apb1_div" },
+
+	{ STM32F4_RCC_APB2ENR,  0,	"tim1",		"apb2_mul" },
+	{ STM32F4_RCC_APB2ENR,  1,	"tim8",		"apb2_mul" },
+	{ STM32F4_RCC_APB2ENR,  4,	"usart1",	"apb2_div" },
+	{ STM32F4_RCC_APB2ENR,  5,	"usart6",	"apb2_div" },
+	{ STM32F4_RCC_APB2ENR,  8,	"adc1",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR,  9,	"adc2",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 10,	"adc3",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 11,	"sdio",		"pll48" },
+	{ STM32F4_RCC_APB2ENR, 12,	"spi1",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 13,	"spi4",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 14,	"syscfg",	"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 16,	"tim9",		"apb2_mul" },
+	{ STM32F4_RCC_APB2ENR, 17,	"tim10",	"apb2_mul" },
+	{ STM32F4_RCC_APB2ENR, 18,	"tim11",	"apb2_mul" },
+	{ STM32F4_RCC_APB2ENR, 20,	"spi5",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 21,	"spi6",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 22,	"sai1",		"apb2_div" },
+	{ STM32F4_RCC_APB2ENR, 26,	"ltdc",		"apb2_div" },
+};
+
+/*
+ * MAX_CLKS is the maximum value in the enumeration below plus the combined
+ * hweight of stm32f42xx_gate_map (plus one).
+ */
+#define MAX_CLKS 74
+
+enum { SYSTICK, FCLK };
+
+/*
+ * This bitmask tells us which bit offsets (0..192) on STM32F4[23]xxx
+ * have gate bits associated with them. Its combined hweight is 71.
+ */
+static const u64 stm32f42xx_gate_map[] = { 0x000000f17ef417ffull,
+					   0x0000000000000001ull,
+					   0x04777f33f6fec9ffull };
+
+static struct clk *clks[MAX_CLKS];
+static DEFINE_SPINLOCK(stm32f4_clk_lock);
+static void __iomem *base;
+
+/*
+ * "Multiplier" device for APBx clocks.
+ *
+ * The APBx dividers are power-of-two dividers and, if *not* running in 1:1
+ * mode, they also tap out the one of the low order state bits to run the
+ * timers. ST datasheets represent this feature as a (conditional) clock
+ * multiplier.
+ */
+struct clk_apb_mul {
+	struct clk_hw hw;
+	u8 bit_idx;
+};
+
+#define to_clk_apb_mul(_hw) container_of(_hw, struct clk_apb_mul, hw)
+
+static unsigned long clk_apb_mul_recalc_rate(struct clk_hw *hw,
+					     unsigned long parent_rate)
+{
+	struct clk_apb_mul *am = to_clk_apb_mul(hw);
+
+	if (readl(base + STM32F4_RCC_CFGR) & BIT(am->bit_idx))
+		return parent_rate * 2;
+
+	return parent_rate;
+}
+
+static long clk_apb_mul_round_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long *prate)
+{
+	struct clk_apb_mul *am = to_clk_apb_mul(hw);
+	unsigned long mult = 1;
+
+	if (readl(base + STM32F4_RCC_CFGR) & BIT(am->bit_idx))
+		mult = 2;
+
+	if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
+		unsigned long best_parent = rate / mult;
+
+		*prate =
+		    __clk_round_rate(__clk_get_parent(hw->clk), best_parent);
+	}
+
+	return *prate * mult;
+}
+
+static int clk_apb_mul_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	/*
+	 * We must report success but we can do so unconditionally because
+	 * clk_apb_mul_round_rate returns values that ensure this call is a
+	 * nop.
+	 */
+
+	return 0;
+}
+
+static const struct clk_ops clk_apb_mul_factor_ops = {
+	.round_rate = clk_apb_mul_round_rate,
+	.set_rate = clk_apb_mul_set_rate,
+	.recalc_rate = clk_apb_mul_recalc_rate,
+};
+
+static struct clk *clk_register_apb_mul(struct device *dev, const char *name,
+					const char *parent_name,
+					unsigned long flags, u8 bit_idx)
+{
+	struct clk_apb_mul *am;
+	struct clk_init_data init;
+	struct clk *clk;
+
+	am = kzalloc(sizeof(*am), GFP_KERNEL);
+	if (!am)
+		return ERR_PTR(-ENOMEM);
+
+	am->bit_idx = bit_idx;
+	am->hw.init = &init;
+
+	init.name = name;
+	init.ops = &clk_apb_mul_factor_ops;
+	init.flags = flags;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	clk = clk_register(dev, &am->hw);
+
+	if (IS_ERR(clk))
+		kfree(am);
+
+	return clk;
+}
+
+/*
+ * Decode current PLL state and (statically) model the state we inherit from
+ * the bootloader.
+ */
+static void stm32f4_rcc_register_pll(const char *hse_clk, const char *hsi_clk)
+{
+	unsigned long pllcfgr = readl(base + STM32F4_RCC_PLLCFGR);
+
+	unsigned long pllm   = pllcfgr & 0x3f;
+	unsigned long plln   = (pllcfgr >> 6) & 0x1ff;
+	unsigned long pllp   = BIT(((pllcfgr >> 16) & 3) + 1);
+	const char   *pllsrc = pllcfgr & BIT(22) ? hse_clk : hsi_clk;
+	unsigned long pllq   = (pllcfgr >> 24) & 0xf;
+
+	clk_register_fixed_factor(NULL, "vco", pllsrc, 0, plln, pllm);
+	clk_register_fixed_factor(NULL, "pll", "vco", 0, 1, pllp);
+	clk_register_fixed_factor(NULL, "pll48", "vco", 0, 1, pllq);
+}
+
+/*
+ * Converts the primary and secondary indices (as they appear in DT) to an
+ * offset into our struct clock array.
+ */
+static int stm32f4_rcc_lookup_clk_idx(u8 primary, u8 secondary)
+{
+	u64 table[ARRAY_SIZE(stm32f42xx_gate_map)];
+
+	if (primary == 1) {
+		if (WARN_ON(secondary > FCLK))
+			return -EINVAL;
+		return secondary;
+	}
+
+	memcpy(table, stm32f42xx_gate_map, sizeof(table));
+
+	/* only bits set in table can be used as indices */
+	if (WARN_ON(secondary > 8 * sizeof(table) ||
+		    0 == (table[BIT_ULL_WORD(secondary)] &
+			  BIT_ULL_MASK(secondary))))
+		return -EINVAL;
+
+	/* mask out bits above our current index */
+	table[BIT_ULL_WORD(secondary)] &=
+	    GENMASK_ULL(secondary % BITS_PER_LONG_LONG, 0);
+
+	return FCLK + hweight64(table[0]) +
+	       (BIT_ULL_WORD(secondary) >= 1 ? hweight64(table[1]) : 0) +
+	       (BIT_ULL_WORD(secondary) >= 2 ? hweight64(table[2]) : 0);
+}
+
+static struct clk *
+stm32f4_rcc_lookup_clk(struct of_phandle_args *clkspec, void *data)
+{
+	int i = stm32f4_rcc_lookup_clk_idx(clkspec->args[0], clkspec->args[1]);
+
+	if (i < 0)
+		return ERR_PTR(-EINVAL);
+
+	return clks[i];
+}
+
+static const char *sys_parents[] __initdata =   { "hsi", NULL, "pll" };
+
+static const struct clk_div_table ahb_div_table[] = {
+	{ 0x0,   1 }, { 0x1,   1 }, { 0x2,   1 }, { 0x3,   1 },
+	{ 0x4,   1 }, { 0x5,   1 }, { 0x6,   1 }, { 0x7,   1 },
+	{ 0x8,   2 }, { 0x9,   4 }, { 0xa,   8 }, { 0xb,  16 },
+	{ 0xc,  64 }, { 0xd, 128 }, { 0xe, 256 }, { 0xf, 512 },
+	{ 0 },
+};
+
+static const struct clk_div_table apb_div_table[] = {
+	{ 0,  1 }, { 0,  1 }, { 0,  1 }, { 0,  1 },
+	{ 4,  2 }, { 5,  4 }, { 6,  8 }, { 7, 16 },
+	{ 0 },
+};
+
+static void __init stm32f4_rcc_init(struct device_node *np)
+{
+	const char *hse_clk;
+	int n;
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_err("%s: unable to map resource", np->name);
+		return;
+	}
+
+	hse_clk = of_clk_get_parent_name(np, 0);
+
+	clk_register_fixed_rate_with_accuracy(NULL, "hsi", NULL, 0,
+			16000000, 160000);
+	stm32f4_rcc_register_pll(hse_clk, "hsi");
+
+	sys_parents[1] = hse_clk;
+	clk_register_mux_table(
+	    NULL, "sys", sys_parents, ARRAY_SIZE(sys_parents), 0,
+	    base + STM32F4_RCC_CFGR, 0, 3, 0, NULL, &stm32f4_clk_lock);
+
+	clk_register_divider_table(NULL, "ahb_div", "sys",
+				   CLK_SET_RATE_PARENT, base + STM32F4_RCC_CFGR,
+				   4, 4, 0, ahb_div_table, &stm32f4_clk_lock);
+
+	clk_register_divider_table(NULL, "apb1_div", "ahb_div",
+				   CLK_SET_RATE_PARENT, base + STM32F4_RCC_CFGR,
+				   10, 3, 0, apb_div_table, &stm32f4_clk_lock);
+	clk_register_apb_mul(NULL, "apb1_mul", "apb1_div",
+			     CLK_SET_RATE_PARENT, 12);
+
+	clk_register_divider_table(NULL, "apb2_div", "ahb_div",
+				   CLK_SET_RATE_PARENT, base + STM32F4_RCC_CFGR,
+				   13, 3, 0, apb_div_table, &stm32f4_clk_lock);
+	clk_register_apb_mul(NULL, "apb2_mul", "apb2_div",
+			     CLK_SET_RATE_PARENT, 15);
+
+	clks[SYSTICK] = clk_register_fixed_factor(NULL, "systick", "ahb_div",
+						  0, 1, 8);
+	clks[FCLK] = clk_register_fixed_factor(NULL, "fclk", "ahb_div",
+					       0, 1, 1);
+
+	for (n = 0; n < ARRAY_SIZE(stm32f4_gates); n++) {
+		const struct stm32f4_gate_data *gd = &stm32f4_gates[n];
+		unsigned int secondary =
+		    8 * (gd->offset - STM32F4_RCC_AHB1ENR) + gd->bit_idx;
+		int idx = stm32f4_rcc_lookup_clk_idx(0, secondary);
+
+		if (idx < 0)
+			goto fail;
+
+		clks[idx] = clk_register_gate(
+		    NULL, gd->name, gd->parent_name, gd->flags,
+		    base + gd->offset, gd->bit_idx, 0, &stm32f4_clk_lock);
+
+		if (IS_ERR(clks[n])) {
+			pr_err("%s: Unable to register leaf clock %s\n",
+			       np->full_name, gd->name);
+			goto fail;
+		}
+	}
+
+	of_clk_add_provider(np, stm32f4_rcc_lookup_clk, NULL);
+	return;
+fail:
+	iounmap(base);
+}
+CLK_OF_DECLARE(stm32f4_rcc, "st,stm32f42xx-rcc", stm32f4_rcc_init);