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Subject[PATCH v2 3/4] clk: stm32: Add clock driver for STM32F4[23]xxx devices
Date
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 (for non-regression only) on an STM32F429I-Discovery
boards. The clock counts for TIM2, USART1 and SYSTICK are all set correctly
and time and the wall clock looks OK when checked with a stopwatch.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
---
drivers/clk/Makefile | 1 +
drivers/clk/clk-stm32f4.c | 364 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 365 insertions(+)
create mode 100644 drivers/clk/clk-stm32f4.c

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d2d5e6c..79cd0d4 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_COMMON_CLK_RK808) += clk-rk808.o
obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o
obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o
obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o
+obj-$(CONFIG_ARCH_STM32) += clk-stm32f4.o
obj-$(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 0000000..68f9962
--- /dev/null
+++ b/drivers/clk/clk-stm32f4.c
@@ -0,0 +1,364 @@
+/*
+ * Author: Daniel Thompson <daniel.thompson@linaro.org>
+ *
+ * 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.h>
+#include <linux/clkdev.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <linux/debugfs.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[] = { 0x000000f17ef417ff,
+ 0x0000000000000001,
+ 0x04777f33f6fec9ff };
+
+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)
+{
+ return 0;
+}
+
+static 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,
+};
+
+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 | CLK_IS_BASIC;
+ 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 unsigned int stm32f4_rcc_lookup_clk_idx(u8 primary, u8 secondary)
+{
+ u64 table[ARRAY_SIZE(stm32f42xx_gate_map)];
+
+ if (primary == 1) {
+ BUG_ON(secondary > FCLK);
+ return secondary;
+ }
+
+ memcpy(table, stm32f42xx_gate_map, sizeof(table));
+
+ /* only bits set in table can be used as indices */
+ BUG_ON(secondary > 8 * sizeof(table) ||
+ 0 == (table[BIT_ULL_WORD(secondary)] & BIT_ULL_MASK(secondary)));
+
+ /* 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);
+}
+
+struct clk *stm32f4_rcc_lookup_clk(struct of_phandle_args *clkspec, void *data)
+{
+ return clks[stm32f4_rcc_lookup_clk_idx(clkspec->args[0],
+ clkspec->args[1])];
+}
+
+static const char __initdata *sys_parents[] = { "hsi", NULL, "pll" };
+
+static 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 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;
+ unsigned int idx = stm32f4_rcc_lookup_clk_idx(0, secondary);
+
+ 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);
--
2.1.0


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