clk: stm32mp1: add clock tree initialization
add binding and code for clock tree initialization from device tree
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/drivers/clk/clk_stm32mp1.c b/drivers/clk/clk_stm32mp1.c
index 0ea2035..55b0f79 100644
--- a/drivers/clk/clk_stm32mp1.c
+++ b/drivers/clk/clk_stm32mp1.c
@@ -12,10 +12,21 @@
#include <spl.h>
#include <syscon.h>
#include <linux/io.h>
+#include <linux/iopoll.h>
#include <dt-bindings/clock/stm32mp1-clks.h>
+#include <dt-bindings/clock/stm32mp1-clksrc.h>
+
+#if !defined(CONFIG_SPL) || defined(CONFIG_SPL_BUILD)
+/* activate clock tree initialization in the driver */
+#define STM32MP1_CLOCK_TREE_INIT
+#endif
#define MAX_HSI_HZ 64000000
+/* TIMEOUT */
+#define TIMEOUT_200MS 200000
+#define TIMEOUT_1S 1000000
+
/* RCC registers */
#define RCC_OCENSETR 0x0C
#define RCC_OCENCLRR 0x10
@@ -1079,6 +1090,565 @@
return rate;
}
+#ifdef STM32MP1_CLOCK_TREE_INIT
+static void stm32mp1_ls_osc_set(int enable, fdt_addr_t rcc, u32 offset,
+ u32 mask_on)
+{
+ u32 address = rcc + offset;
+
+ if (enable)
+ setbits_le32(address, mask_on);
+ else
+ clrbits_le32(address, mask_on);
+}
+
+static void stm32mp1_hs_ocs_set(int enable, fdt_addr_t rcc, u32 mask_on)
+{
+ if (enable)
+ setbits_le32(rcc + RCC_OCENSETR, mask_on);
+ else
+ setbits_le32(rcc + RCC_OCENCLRR, mask_on);
+}
+
+static int stm32mp1_osc_wait(int enable, fdt_addr_t rcc, u32 offset,
+ u32 mask_rdy)
+{
+ u32 mask_test = 0;
+ u32 address = rcc + offset;
+ u32 val;
+ int ret;
+
+ if (enable)
+ mask_test = mask_rdy;
+
+ ret = readl_poll_timeout(address, val,
+ (val & mask_rdy) == mask_test,
+ TIMEOUT_1S);
+
+ if (ret)
+ pr_err("OSC %x @ %x timeout for enable=%d : 0x%x\n",
+ mask_rdy, address, enable, readl(address));
+
+ return ret;
+}
+
+static void stm32mp1_lse_enable(fdt_addr_t rcc, int bypass, int lsedrv)
+{
+ u32 value;
+
+ if (bypass)
+ setbits_le32(rcc + RCC_BDCR, RCC_BDCR_LSEBYP);
+
+ /*
+ * warning: not recommended to switch directly from "high drive"
+ * to "medium low drive", and vice-versa.
+ */
+ value = (readl(rcc + RCC_BDCR) & RCC_BDCR_LSEDRV_MASK)
+ >> RCC_BDCR_LSEDRV_SHIFT;
+
+ while (value != lsedrv) {
+ if (value > lsedrv)
+ value--;
+ else
+ value++;
+
+ clrsetbits_le32(rcc + RCC_BDCR,
+ RCC_BDCR_LSEDRV_MASK,
+ value << RCC_BDCR_LSEDRV_SHIFT);
+ }
+
+ stm32mp1_ls_osc_set(1, rcc, RCC_BDCR, RCC_BDCR_LSEON);
+}
+
+static void stm32mp1_lse_wait(fdt_addr_t rcc)
+{
+ stm32mp1_osc_wait(1, rcc, RCC_BDCR, RCC_BDCR_LSERDY);
+}
+
+static void stm32mp1_lsi_set(fdt_addr_t rcc, int enable)
+{
+ stm32mp1_ls_osc_set(enable, rcc, RCC_RDLSICR, RCC_RDLSICR_LSION);
+ stm32mp1_osc_wait(enable, rcc, RCC_RDLSICR, RCC_RDLSICR_LSIRDY);
+}
+
+static void stm32mp1_hse_enable(fdt_addr_t rcc, int bypass, int css)
+{
+ if (bypass)
+ setbits_le32(rcc + RCC_OCENSETR, RCC_OCENR_HSEBYP);
+
+ stm32mp1_hs_ocs_set(1, rcc, RCC_OCENR_HSEON);
+ stm32mp1_osc_wait(1, rcc, RCC_OCRDYR, RCC_OCRDYR_HSERDY);
+
+ if (css)
+ setbits_le32(rcc + RCC_OCENSETR, RCC_OCENR_HSECSSON);
+}
+
+static void stm32mp1_csi_set(fdt_addr_t rcc, int enable)
+{
+ stm32mp1_ls_osc_set(enable, rcc, RCC_OCENSETR, RCC_OCENR_CSION);
+ stm32mp1_osc_wait(enable, rcc, RCC_OCRDYR, RCC_OCRDYR_CSIRDY);
+}
+
+static void stm32mp1_hsi_set(fdt_addr_t rcc, int enable)
+{
+ stm32mp1_hs_ocs_set(enable, rcc, RCC_OCENR_HSION);
+ stm32mp1_osc_wait(enable, rcc, RCC_OCRDYR, RCC_OCRDYR_HSIRDY);
+}
+
+static int stm32mp1_set_hsidiv(fdt_addr_t rcc, u8 hsidiv)
+{
+ u32 address = rcc + RCC_OCRDYR;
+ u32 val;
+ int ret;
+
+ clrsetbits_le32(rcc + RCC_HSICFGR,
+ RCC_HSICFGR_HSIDIV_MASK,
+ RCC_HSICFGR_HSIDIV_MASK & hsidiv);
+
+ ret = readl_poll_timeout(address, val,
+ val & RCC_OCRDYR_HSIDIVRDY,
+ TIMEOUT_200MS);
+ if (ret)
+ pr_err("HSIDIV failed @ 0x%x: 0x%x\n",
+ address, readl(address));
+
+ return ret;
+}
+
+static int stm32mp1_hsidiv(fdt_addr_t rcc, ulong hsifreq)
+{
+ u8 hsidiv;
+ u32 hsidivfreq = MAX_HSI_HZ;
+
+ for (hsidiv = 0; hsidiv < 4; hsidiv++,
+ hsidivfreq = hsidivfreq / 2)
+ if (hsidivfreq == hsifreq)
+ break;
+
+ if (hsidiv == 4) {
+ pr_err("clk-hsi frequency invalid");
+ return -1;
+ }
+
+ if (hsidiv > 0)
+ return stm32mp1_set_hsidiv(rcc, hsidiv);
+
+ return 0;
+}
+
+static void pll_start(struct stm32mp1_clk_priv *priv, int pll_id)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+
+ writel(RCC_PLLNCR_PLLON, priv->base + pll[pll_id].pllxcr);
+}
+
+static int pll_output(struct stm32mp1_clk_priv *priv, int pll_id, int output)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+ u32 pllxcr = priv->base + pll[pll_id].pllxcr;
+ u32 val;
+ int ret;
+
+ ret = readl_poll_timeout(pllxcr, val, val & RCC_PLLNCR_PLLRDY,
+ TIMEOUT_200MS);
+
+ if (ret) {
+ pr_err("PLL%d start failed @ 0x%x: 0x%x\n",
+ pll_id, pllxcr, readl(pllxcr));
+ return ret;
+ }
+
+ /* start the requested output */
+ setbits_le32(pllxcr, output << RCC_PLLNCR_DIVEN_SHIFT);
+
+ return 0;
+}
+
+static int pll_stop(struct stm32mp1_clk_priv *priv, int pll_id)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+ u32 pllxcr = priv->base + pll[pll_id].pllxcr;
+ u32 val;
+
+ /* stop all output */
+ clrbits_le32(pllxcr,
+ RCC_PLLNCR_DIVPEN | RCC_PLLNCR_DIVQEN | RCC_PLLNCR_DIVREN);
+
+ /* stop PLL */
+ clrbits_le32(pllxcr, RCC_PLLNCR_PLLON);
+
+ /* wait PLL stopped */
+ return readl_poll_timeout(pllxcr, val, (val & RCC_PLLNCR_PLLRDY) == 0,
+ TIMEOUT_200MS);
+}
+
+static void pll_config_output(struct stm32mp1_clk_priv *priv,
+ int pll_id, u32 *pllcfg)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+ fdt_addr_t rcc = priv->base;
+ u32 value;
+
+ value = (pllcfg[PLLCFG_P] << RCC_PLLNCFGR2_DIVP_SHIFT)
+ & RCC_PLLNCFGR2_DIVP_MASK;
+ value |= (pllcfg[PLLCFG_Q] << RCC_PLLNCFGR2_DIVQ_SHIFT)
+ & RCC_PLLNCFGR2_DIVQ_MASK;
+ value |= (pllcfg[PLLCFG_R] << RCC_PLLNCFGR2_DIVR_SHIFT)
+ & RCC_PLLNCFGR2_DIVR_MASK;
+ writel(value, rcc + pll[pll_id].pllxcfgr2);
+}
+
+static int pll_config(struct stm32mp1_clk_priv *priv, int pll_id,
+ u32 *pllcfg, u32 fracv)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+ fdt_addr_t rcc = priv->base;
+ enum stm32mp1_plltype type = pll[pll_id].plltype;
+ int src;
+ ulong refclk;
+ u8 ifrge = 0;
+ u32 value;
+
+ src = readl(priv->base + pll[pll_id].rckxselr) & RCC_SELR_SRC_MASK;
+
+ refclk = stm32mp1_clk_get_fixed(priv, pll[pll_id].refclk[src]) /
+ (pllcfg[PLLCFG_M] + 1);
+
+ if (refclk < (stm32mp1_pll[type].refclk_min * 1000000) ||
+ refclk > (stm32mp1_pll[type].refclk_max * 1000000)) {
+ debug("invalid refclk = %x\n", (u32)refclk);
+ return -EINVAL;
+ }
+ if (type == PLL_800 && refclk >= 8000000)
+ ifrge = 1;
+
+ value = (pllcfg[PLLCFG_N] << RCC_PLLNCFGR1_DIVN_SHIFT)
+ & RCC_PLLNCFGR1_DIVN_MASK;
+ value |= (pllcfg[PLLCFG_M] << RCC_PLLNCFGR1_DIVM_SHIFT)
+ & RCC_PLLNCFGR1_DIVM_MASK;
+ value |= (ifrge << RCC_PLLNCFGR1_IFRGE_SHIFT)
+ & RCC_PLLNCFGR1_IFRGE_MASK;
+ writel(value, rcc + pll[pll_id].pllxcfgr1);
+
+ /* fractional configuration: load sigma-delta modulator (SDM) */
+
+ /* Write into FRACV the new fractional value , and FRACLE to 0 */
+ writel(fracv << RCC_PLLNFRACR_FRACV_SHIFT,
+ rcc + pll[pll_id].pllxfracr);
+
+ /* Write FRACLE to 1 : FRACV value is loaded into the SDM */
+ setbits_le32(rcc + pll[pll_id].pllxfracr,
+ RCC_PLLNFRACR_FRACLE);
+
+ pll_config_output(priv, pll_id, pllcfg);
+
+ return 0;
+}
+
+static void pll_csg(struct stm32mp1_clk_priv *priv, int pll_id, u32 *csg)
+{
+ const struct stm32mp1_clk_pll *pll = priv->data->pll;
+ u32 pllxcsg;
+
+ pllxcsg = ((csg[PLLCSG_MOD_PER] << RCC_PLLNCSGR_MOD_PER_SHIFT) &
+ RCC_PLLNCSGR_MOD_PER_MASK) |
+ ((csg[PLLCSG_INC_STEP] << RCC_PLLNCSGR_INC_STEP_SHIFT) &
+ RCC_PLLNCSGR_INC_STEP_MASK) |
+ ((csg[PLLCSG_SSCG_MODE] << RCC_PLLNCSGR_SSCG_MODE_SHIFT) &
+ RCC_PLLNCSGR_SSCG_MODE_MASK);
+
+ writel(pllxcsg, priv->base + pll[pll_id].pllxcsgr);
+}
+
+static int set_clksrc(struct stm32mp1_clk_priv *priv, unsigned int clksrc)
+{
+ u32 address = priv->base + (clksrc >> 4);
+ u32 val;
+ int ret;
+
+ clrsetbits_le32(address, RCC_SELR_SRC_MASK, clksrc & RCC_SELR_SRC_MASK);
+ ret = readl_poll_timeout(address, val, val & RCC_SELR_SRCRDY,
+ TIMEOUT_200MS);
+ if (ret)
+ pr_err("CLKSRC %x start failed @ 0x%x: 0x%x\n",
+ clksrc, address, readl(address));
+
+ return ret;
+}
+
+static int set_clkdiv(unsigned int clkdiv, u32 address)
+{
+ u32 val;
+ int ret;
+
+ clrsetbits_le32(address, RCC_DIVR_DIV_MASK, clkdiv & RCC_DIVR_DIV_MASK);
+ ret = readl_poll_timeout(address, val, val & RCC_DIVR_DIVRDY,
+ TIMEOUT_200MS);
+ if (ret)
+ pr_err("CLKDIV %x start failed @ 0x%x: 0x%x\n",
+ clkdiv, address, readl(address));
+
+ return ret;
+}
+
+static void stm32mp1_mco_csg(struct stm32mp1_clk_priv *priv,
+ u32 clksrc, u32 clkdiv)
+{
+ u32 address = priv->base + (clksrc >> 4);
+
+ /*
+ * binding clksrc : bit15-4 offset
+ * bit3: disable
+ * bit2-0: MCOSEL[2:0]
+ */
+ if (clksrc & 0x8) {
+ clrbits_le32(address, RCC_MCOCFG_MCOON);
+ } else {
+ clrsetbits_le32(address,
+ RCC_MCOCFG_MCOSRC_MASK,
+ clksrc & RCC_MCOCFG_MCOSRC_MASK);
+ clrsetbits_le32(address,
+ RCC_MCOCFG_MCODIV_MASK,
+ clkdiv << RCC_MCOCFG_MCODIV_SHIFT);
+ setbits_le32(address, RCC_MCOCFG_MCOON);
+ }
+}
+
+static void set_rtcsrc(struct stm32mp1_clk_priv *priv,
+ unsigned int clksrc,
+ int lse_css)
+{
+ u32 address = priv->base + RCC_BDCR;
+
+ if (readl(address) & RCC_BDCR_RTCCKEN)
+ goto skip_rtc;
+
+ if (clksrc == CLK_RTC_DISABLED)
+ goto skip_rtc;
+
+ clrsetbits_le32(address,
+ RCC_BDCR_RTCSRC_MASK,
+ clksrc << RCC_BDCR_RTCSRC_SHIFT);
+
+ setbits_le32(address, RCC_BDCR_RTCCKEN);
+
+skip_rtc:
+ if (lse_css)
+ setbits_le32(address, RCC_BDCR_LSECSSON);
+}
+
+static void pkcs_config(struct stm32mp1_clk_priv *priv, u32 pkcs)
+{
+ u32 address = priv->base + ((pkcs >> 4) & 0xFFF);
+ u32 value = pkcs & 0xF;
+ u32 mask = 0xF;
+
+ if (pkcs & BIT(31)) {
+ mask <<= 4;
+ value <<= 4;
+ }
+ clrsetbits_le32(address, mask, value);
+}
+
+static int stm32mp1_clktree(struct udevice *dev)
+{
+ struct stm32mp1_clk_priv *priv = dev_get_priv(dev);
+ fdt_addr_t rcc = priv->base;
+ unsigned int clksrc[CLKSRC_NB];
+ unsigned int clkdiv[CLKDIV_NB];
+ unsigned int pllcfg[_PLL_NB][PLLCFG_NB];
+ ofnode plloff[_PLL_NB];
+ int ret;
+ int i, len;
+ int lse_css = 0;
+ const u32 *pkcs_cell;
+
+ /* check mandatory field */
+ ret = dev_read_u32_array(dev, "st,clksrc", clksrc, CLKSRC_NB);
+ if (ret < 0) {
+ debug("field st,clksrc invalid: error %d\n", ret);
+ return -FDT_ERR_NOTFOUND;
+ }
+
+ ret = dev_read_u32_array(dev, "st,clkdiv", clkdiv, CLKDIV_NB);
+ if (ret < 0) {
+ debug("field st,clkdiv invalid: error %d\n", ret);
+ return -FDT_ERR_NOTFOUND;
+ }
+
+ /* check mandatory field in each pll */
+ for (i = 0; i < _PLL_NB; i++) {
+ char name[12];
+
+ sprintf(name, "st,pll@%d", i);
+ plloff[i] = dev_read_subnode(dev, name);
+ if (!ofnode_valid(plloff[i]))
+ continue;
+ ret = ofnode_read_u32_array(plloff[i], "cfg",
+ pllcfg[i], PLLCFG_NB);
+ if (ret < 0) {
+ debug("field cfg invalid: error %d\n", ret);
+ return -FDT_ERR_NOTFOUND;
+ }
+ }
+
+ debug("configuration MCO\n");
+ stm32mp1_mco_csg(priv, clksrc[CLKSRC_MCO1], clkdiv[CLKDIV_MCO1]);
+ stm32mp1_mco_csg(priv, clksrc[CLKSRC_MCO2], clkdiv[CLKDIV_MCO2]);
+
+ debug("switch ON osillator\n");
+ /*
+ * switch ON oscillator found in device-tree,
+ * HSI already ON after bootrom
+ */
+ if (priv->osc[_LSI])
+ stm32mp1_lsi_set(rcc, 1);
+
+ if (priv->osc[_LSE]) {
+ int bypass;
+ int lsedrv;
+ struct udevice *dev = priv->osc_dev[_LSE];
+
+ bypass = dev_read_bool(dev, "st,bypass");
+ 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);
+ }
+
+ if (priv->osc[_HSE]) {
+ int bypass, css;
+ struct udevice *dev = priv->osc_dev[_HSE];
+
+ bypass = dev_read_bool(dev, "st,bypass");
+ css = dev_read_bool(dev, "st,css");
+
+ stm32mp1_hse_enable(rcc, bypass, css);
+ }
+ /* CSI is mandatory for automatic I/O compensation (SYSCFG_CMPCR)
+ * => switch on CSI even if node is not present in device tree
+ */
+ stm32mp1_csi_set(rcc, 1);
+
+ /* come back to HSI */
+ debug("come back to HSI\n");
+ set_clksrc(priv, CLK_MPU_HSI);
+ set_clksrc(priv, CLK_AXI_HSI);
+ set_clksrc(priv, CLK_MCU_HSI);
+
+ debug("pll stop\n");
+ for (i = 0; i < _PLL_NB; i++)
+ pll_stop(priv, i);
+
+ /* configure HSIDIV */
+ debug("configure HSIDIV\n");
+ if (priv->osc[_HSI])
+ stm32mp1_hsidiv(rcc, priv->osc[_HSI]);
+
+ /* select DIV */
+ debug("select DIV\n");
+ /* no ready bit when MPUSRC != CLK_MPU_PLL1P_DIV, MPUDIV is disabled */
+ writel(clkdiv[CLKDIV_MPU] & RCC_DIVR_DIV_MASK, rcc + RCC_MPCKDIVR);
+ set_clkdiv(clkdiv[CLKDIV_AXI], rcc + RCC_AXIDIVR);
+ set_clkdiv(clkdiv[CLKDIV_APB4], rcc + RCC_APB4DIVR);
+ set_clkdiv(clkdiv[CLKDIV_APB5], rcc + RCC_APB5DIVR);
+ set_clkdiv(clkdiv[CLKDIV_MCU], rcc + RCC_MCUDIVR);
+ set_clkdiv(clkdiv[CLKDIV_APB1], rcc + RCC_APB1DIVR);
+ set_clkdiv(clkdiv[CLKDIV_APB2], rcc + RCC_APB2DIVR);
+ set_clkdiv(clkdiv[CLKDIV_APB3], rcc + RCC_APB3DIVR);
+
+ /* no ready bit for RTC */
+ writel(clkdiv[CLKDIV_RTC] & RCC_DIVR_DIV_MASK, rcc + RCC_RTCDIVR);
+
+ /* configure PLLs source */
+ debug("configure PLLs source\n");
+ set_clksrc(priv, clksrc[CLKSRC_PLL12]);
+ set_clksrc(priv, clksrc[CLKSRC_PLL3]);
+ set_clksrc(priv, clksrc[CLKSRC_PLL4]);
+
+ /* configure and start PLLs */
+ debug("configure PLLs\n");
+ for (i = 0; i < _PLL_NB; i++) {
+ u32 fracv;
+ u32 csg[PLLCSG_NB];
+
+ debug("configure PLL %d @ %d\n", i,
+ ofnode_to_offset(plloff[i]));
+ if (!ofnode_valid(plloff[i]))
+ continue;
+
+ fracv = ofnode_read_u32_default(plloff[i], "frac", 0);
+ pll_config(priv, i, pllcfg[i], fracv);
+ ret = ofnode_read_u32_array(plloff[i], "csg", csg, PLLCSG_NB);
+ if (!ret) {
+ pll_csg(priv, i, csg);
+ } else if (ret != -FDT_ERR_NOTFOUND) {
+ debug("invalid csg node for pll@%d res=%d\n", i, ret);
+ return ret;
+ }
+ pll_start(priv, i);
+ }
+
+ /* wait and start PLLs ouptut when ready */
+ for (i = 0; i < _PLL_NB; i++) {
+ if (!ofnode_valid(plloff[i]))
+ continue;
+ debug("output PLL %d\n", i);
+ pll_output(priv, i, pllcfg[i][PLLCFG_O]);
+ }
+
+ /* wait LSE ready before to use it */
+ if (priv->osc[_LSE])
+ stm32mp1_lse_wait(rcc);
+
+ /* configure with expected clock source */
+ debug("CLKSRC\n");
+ set_clksrc(priv, clksrc[CLKSRC_MPU]);
+ set_clksrc(priv, clksrc[CLKSRC_AXI]);
+ set_clksrc(priv, clksrc[CLKSRC_MCU]);
+ set_rtcsrc(priv, clksrc[CLKSRC_RTC], lse_css);
+
+ /* configure PKCK */
+ debug("PKCK\n");
+ pkcs_cell = dev_read_prop(dev, "st,pkcs", &len);
+ if (pkcs_cell) {
+ bool ckper_disabled = false;
+
+ for (i = 0; i < len / sizeof(u32); i++) {
+ u32 pkcs = (u32)fdt32_to_cpu(pkcs_cell[i]);
+
+ if (pkcs == CLK_CKPER_DISABLED) {
+ ckper_disabled = true;
+ continue;
+ }
+ pkcs_config(priv, pkcs);
+ }
+ /* CKPER is source for some peripheral clock
+ * (FMC-NAND / QPSI-NOR) and switching source is allowed
+ * only if previous clock is still ON
+ * => deactivated CKPER only after switching clock
+ */
+ if (ckper_disabled)
+ pkcs_config(priv, CLK_CKPER_DISABLED);
+ }
+
+ debug("oscillator off\n");
+ /* switch OFF HSI if not found in device-tree */
+ if (!priv->osc[_HSI])
+ stm32mp1_hsi_set(rcc, 0);
+
+ /* Software Self-Refresh mode (SSR) during DDR initilialization */
+ clrsetbits_le32(priv->base + RCC_DDRITFCR,
+ RCC_DDRITFCR_DDRCKMOD_MASK,
+ RCC_DDRITFCR_DDRCKMOD_SSR <<
+ RCC_DDRITFCR_DDRCKMOD_SHIFT);
+
+ return 0;
+}
+#endif /* STM32MP1_CLOCK_TREE_INIT */
+
static void stm32mp1_osc_clk_init(const char *name,
struct stm32mp1_clk_priv *priv,
int index)
@@ -1133,6 +1703,12 @@
stm32mp1_osc_init(dev);
+#ifdef STM32MP1_CLOCK_TREE_INIT
+ /* clock tree init is done only one time, before relocation */
+ if (!(gd->flags & GD_FLG_RELOC))
+ result = stm32mp1_clktree(dev);
+#endif
+
return result;
}