stm32mp1: clk: support digital bypass

HSE and LSE bypass shall support both analog and digital signals.
This patch add a way to select digital bypas case in the device tree
and set the associated bit DIGBYP in RCC_BDCR and RCC_OCEN register
during clock tree initialization.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

diff --git a/doc/device-tree-bindings/clock/st,stm32mp1.txt b/doc/device-tree-bindings/clock/st,stm32mp1.txt
index c29d90f..6a9397e 100644 (file)
--- a/doc/device-tree-bindings/clock/st,stm32mp1.txt
+++ b/doc/device-tree-bindings/clock/st,stm32mp1.txt
@@ -170,8 +170,10 @@ Optional properties :
 
 a) for external oscillator: "clk-lse", "clk-hse"
 
-       3 optional fields are managed
+       4 optional fields are managed
        - "st,bypass" Configure the oscillator bypass mode (HSEBYP, LSEBYP)
+       - "st,digbypass" Configure the bypass mode as full-swing digital signal
+         (DIGBYP)
        - "st,css" Activate the clock security system (HSECSSON, LSECSSON)
        - "st,drive" (only for LSE) value of the drive for the oscillator
           (see LSEDRV_ define in the file dt-bindings/clock/stm32mp1-clksrc.h)

diff --git a/drivers/clk/clk_stm32mp1.c b/drivers/clk/clk_stm32mp1.c
index 05dc93a..6a8c7b7 100644 (file)
--- a/drivers/clk/clk_stm32mp1.c
+++ b/drivers/clk/clk_stm32mp1.c
@@ -149,6 +149,7 @@
 #define RCC_BDCR_LSEON         BIT(0)
 #define RCC_BDCR_LSEBYP                BIT(1)
 #define RCC_BDCR_LSERDY                BIT(2)
+#define RCC_BDCR_DIGBYP                BIT(3)
 #define RCC_BDCR_LSEDRV_MASK   GENMASK(5, 4)
 #define RCC_BDCR_LSEDRV_SHIFT  4
 #define RCC_BDCR_LSECSSON      BIT(8)
@@ -203,6 +204,7 @@
 /* used for RCC_OCENSETR and RCC_OCENCLRR registers */
 #define RCC_OCENR_HSION                        BIT(0)
 #define RCC_OCENR_CSION                        BIT(4)
+#define RCC_OCENR_DIGBYP               BIT(7)
 #define RCC_OCENR_HSEON                        BIT(8)
 #define RCC_OCENR_HSEBYP               BIT(10)
 #define RCC_OCENR_HSECSSON             BIT(11)
@@ -1202,11 +1204,15 @@ static int stm32mp1_osc_wait(int enable, fdt_addr_t rcc, u32 offset,
        return ret;
 }
 
-static void stm32mp1_lse_enable(fdt_addr_t rcc, int bypass, int lsedrv)
+static void stm32mp1_lse_enable(fdt_addr_t rcc, int bypass, int digbyp,
+                               int lsedrv)
 {
        u32 value;
 
-       if (bypass)
+       if (digbyp)
+               setbits_le32(rcc + RCC_BDCR, RCC_BDCR_DIGBYP);
+
+       if (bypass || digbyp)
                setbits_le32(rcc + RCC_BDCR, RCC_BDCR_LSEBYP);
 
        /*
@@ -1241,9 +1247,11 @@ static void stm32mp1_lsi_set(fdt_addr_t rcc, int enable)
        stm32mp1_osc_wait(enable, rcc, RCC_RDLSICR, RCC_RDLSICR_LSIRDY);
 }
 
-static void stm32mp1_hse_enable(fdt_addr_t rcc, int bypass, int css)
+static void stm32mp1_hse_enable(fdt_addr_t rcc, int bypass, int digbyp, int css)
 {
-       if (bypass)
+       if (digbyp)
+               setbits_le32(rcc + RCC_OCENSETR, RCC_OCENR_DIGBYP);
+       if (bypass || digbyp)
                setbits_le32(rcc + RCC_OCENSETR, RCC_OCENR_HSEBYP);
 
        stm32mp1_hs_ocs_set(1, rcc, RCC_OCENR_HSEON);
@@ -1606,26 +1614,27 @@ static int stm32mp1_clktree(struct udevice *dev)
                stm32mp1_lsi_set(rcc, 1);
 
        if (priv->osc[_LSE]) {
-               int bypass;
-               int lsedrv;
+               int bypass, digbyp, lsedrv;
                struct udevice *dev = priv->osc_dev[_LSE];
 
                bypass = dev_read_bool(dev, "st,bypass");
+               digbyp = dev_read_bool(dev, "st,digbypass");
                lse_css = dev_read_bool(dev, "st,css");
                lsedrv = dev_read_u32_default(dev, "st,drive",
                                              LSEDRV_MEDIUM_HIGH);
 
-               stm32mp1_lse_enable(rcc, bypass, lsedrv);
+               stm32mp1_lse_enable(rcc, bypass, digbyp, lsedrv);
        }
 
        if (priv->osc[_HSE]) {
-               int bypass, css;
+               int bypass, digbyp, css;
                struct udevice *dev = priv->osc_dev[_HSE];
 
                bypass = dev_read_bool(dev, "st,bypass");
+               digbyp = dev_read_bool(dev, "st,digbypass");
                css = dev_read_bool(dev, "st,css");
 
-               stm32mp1_hse_enable(rcc, bypass, css);
+               stm32mp1_hse_enable(rcc, bypass, digbyp, css);
        }
        /* CSI is mandatory for automatic I/O compensation (SYSCFG_CMPCR)
         * => switch on CSI even if node is not present in device tree